HEY 420 MEMBERS, I TOOK THE TIME TO MAKE AN ALL GARDEN PEST THREAD. IVE NOTICED ALOT OF MY FELLOW MEMBERS HERE ARE HEAVING PEST ISSUES EVEN ON THERE INSIDE GROWS. SO HOPEFULLY THIS GIVES A LITTLE MORE INSIGHT ON WHAT TO LOOK FOR AND HOW TO GET IT UNDER CONTROL. SO STARTING WITH THE MOST COMMON PEST I WILL LIST AND SHARE INFO AND WAYS TO GET RID OF THE PROBLEMS IN YOUR GARDEN 
One bug does not make a problem! In nature, there are always some garden pests chewing on plants; that's just the way it is. However, not all pest damage is significant enough to warrant action. Even the healthiest gardens encounter bugs at one time or another, yet they still produce a beautiful harvest. As gardeners, we must each consider the level of pest activity that we are willing to tolerate.
The best way to maintain a healthy garden is to educate yourself and learn to identify common "bad bugs." Inspect your garden regularly to detect problems early. The sooner a pest is identified the easier it will be to manage using earth-friendly methods. Below we've listed several garden invaders that you may encounter. Click on each pest picture for a description and our list of organic remedies.
Ant
Where: Pestiferous in gardens where they protect aphids and other pest insects.
Aphids
Where: In clusters under leaves and on new growth.
Armyworm
Where: Leaves of lettuce, cole crops, beans, tomatoes and corn.
Asparagus Beetle
Where: One of the most destructive pests of asparagus.
Cabbage Looper
Where: Leaves of cabbage-family plants.
Cabbageworm
Where: Chews irregular holes in leaves (primarily cole crops).
Chinch Bug
Where: On corn and sorghums, also injures small grains and other grass crops.
Colorado Potato Beetle
Where: Leaves of potatoes, tomatoes, and eggplants.
Corn Earworm
Where: One of the most destructive insect pests attacking corn. Also found on cotton and tomatoes.
Cucumber Beetle
Where: Leaves, flowers, and fruits of cucumbers, squash, pumpkins, melons, and other plants.
Cutworm
Where: At night, cutworms clip off seedling stems near or just below the soil surface.
Earwig
Where: Leaves, flowers and shoots of most vegetables, flowers and ornamentals.
European Corn Borer
Where: Leaves, tassels and stalks of corn; also found on peppers, snap beans, potatoes, tomatoes and apples.
Flea Beetle
Where: Chews numerous small holes in the leaves of many crops. Jumps like a flea.
Grasshopper
Where: One of the most destructive insect pests attacking gardens and landscapes.
Leafhopper
Where: Found on a variety of fruit and vegetable crops.
Mexican Bean Beetle
Where: On the underside of the leaves of all bean varieties.
Psyllid
Where: On a variety of plants, including most fruit trees and small fruits, as well as tomato and potato.
Root Maggot
Where: Underground where they attack many vegetable crops including radish, carrot, turnip, and onions.
Slug & Snail
Where: Throughout the United States on a variety of plants as well as on decaying plant material.
Sowbug (Pillbug)
Where: On decaying matter; occasionally on seedlings, new roots and lower leaves.
Spider Mite
Where: In colonies, mostly on the underside of leaves.
Squash Bug
Where: Throughout North America on the leaves and stems of squash and pumpkins.
Thrips
Where: Leaves, fruits and flowers of many plants.
Tomato Hornworm
Where: The most destructive and widely distributed pest of tobacco and tomato plants.
Whitefly
Where: Leaves, flowers and fruits of many vegetable and ornamental plantings.
Wireworm
Where: Underground attacking germinating seeds, roots, and tubers of plants.
Aphid Control
Description: There are approximately 4,000 aphid species found throughout the world. A common pest on many garden vegetables, fruit trees and ornamental plants, these sap-sucking insects are often noticed feeding in clusters or colonies under leaves and on new succulent shoots. Low to moderate numbers are usually not harmful, but heavy infestations may cause leaves to curl, wilting, yellowing, and stunted growth, as well as a general decline in overall plant vigor. Several species will also transmit a number of plant diseases, particularly viruses which they transmit during feeding.
Aphids are small (1/8 inch long), soft bodied, pear-shaped insects that may be green, yellow, brown, red or black in color depending on species and food source. Generally adults are wingless, but some can grow wings, especially if populations are high. They have two whip-like antennae at the tip of the head and a pair of tube-like structures, called cornicles, projecting backward out of their hind end.
Note: As they feed, aphids secrete large amounts of a sticky fluid known as honeydew. This sweet goo drips onto plants, attracting ants and promoting a black sooty mold growth on leaves. Cars and lawn furniture that are under infested trees will also be covered with this sticky fluid.
Life Cycle: In spring wingless female aphids hatch from overwintering eggs and soon give birth to many nymphs (males are not present). Young nymphs increase gradually in size and within a week give birth to many more nymphs. This process is repeated several times and results in huge population explosions. As the colony grows, a few of the females develop wings and fly off to other host plants to start new colonies. In late summer and early fall sexual forms (males and females) develop which mate and lay overwintering eggs. There are many overlapping generations per year.
Note: Most aphids, except for the sexual forms, do not have to mate in order to reproduce, and they produce live young, rather than eggs.
Control: Pinch or prune off heavily infested leaves or other plant parts. Use the Bug Blaster or hose off plants with a strong stream of water to reduce pest numbers. Commercially available beneficial insects, such as ladybugs and lacewing are important natural predators. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas. Horticultural oils should be applied early in the season or late in the fall to destroy overwintering eggs.
Tip: Do not over water or over fertilize - aphids like plants with high nitrogen levels and soft new growth. Try organic fertilizers which release nutrients slowly.
Note: Ants feed on the honeydew that sucking insects produce and will protect these pests from their natural enemies. An application of Tanglefoot Pest Barrier to the stalks of roses and other woody plants will help keep ants away.
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Spider Mite Control
Description: Common across North America, many species of the spider mite (family: Tetranychidae) attack both indoor and outdoor gardens and can be very destructive in greenhouses. They live in colonies, mostly on the underside of leaves and feed by piercing leaf tissue and sucking up the plant fluids. Feeding marks show up as light dots on the leaves; as feeding continues, the leaves turn yellow, and may dry up and drop off. Spider mites are most common in hot, dry conditions and when their natural enemies have been killed off by insecticide use. They are also very prolific, which is why heavy infestations often build up unnoticed before plants begin to show damage. Large populations may be accompanied by fine webbing. Host plants are many and include strawberries, melons, beans, tomatoes, eggplant, ornamental flowers, trees and most houseplants.
Spider mites are not true insects, but are classed as a type of arachnid, relatives of insects that also includes spiders, ticks, and scorpions. Adults are reddish brown or pale in color, oval-shaped, and very small (1/50 inch long) - about the size of the period at the end of this sentence. Immature stages resemble the adults except only smaller.
Life Cycle: Most spider mite species overwinter as eggs on the leaves and bark of host plants. In early spring, as temperatures warm, tiny six-legged larvae begin hatching and feed for a few days before seeking shelter where they molt into the first nymphal stage. Nymphs have eight-legs and pass through two more molts before becoming mature adults. After mating, females are capable of producing as many as 300 eggs over a couple of weeks. Hot, dry weather favors rapid development of these pests. During such conditions the time it takes to pass from egg to adult may occur in as little as 5 days. There are several overlapping generations per year.
Note: Dispersal over a wide area occurs when spider mites are carried on their webbing by the wind.
Control: If pests are found, pinch or prune off infested leaves or other plant parts. Use the Bug Blaster or wash plants with a strong stream of water to reduce pest numbers. Commercially available beneficial insects, such as ladybugs, lacewing, and predatory mites are important natural enemies. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas. Horticultural oils should be applied early in the season or late in the fall to destroy overwintering eggs.
Tip: Control strategies must take into account the fast development time of this pest, especially during warm weather when eggs are laid continuously. Just targeting the adults will do little good - repeat treatments are almost always necessary.
Photo Credit: Jack Kelly Clark
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Thrips Control
Description: There are more than 6,000 thrips species known in the world. A common pest found in greenhouses, and ornamental and vegetable gardens, they damage plants by sucking their juices, and scraping at fruits, flowers and leaves. Leaves may turn pale, splotchy and silvery, then die. Injured plants are twisted, discolored and scarred. Extremely active, thrips feed in large groups and leap or fly away when disturbed. Host plants include onions, beans, carrots, squash and many other garden vegetables and many flowers, especially gladioli and roses.
Adults are very small (less than 1/25 inch) straw-colored or black slender insects with two pairs of feathery wings. Without the use of a hand lens, they resemble tiny dark threads. Both adults and the wingless larvae are attracted to white, yellow and other light colored blossoms and are responsible for spreading tomato spotted wilt virus and impatiens necrotic spot virus.
Life Cycle: Adults and pupae overwinter in garden soil. In spring, newly emerged females insert eggs into the tissues of flowers, leaves or stems. (They do not need to mate for reproduction.) Each female can produce up to 80 eggs, which hatch within days in warm weather, or weeks to months in colder weather. They become wingless larvae (nymphs), which feed on plant sap. After two or more nymphal stages, many thrips drop to the soil to pupate. Emerging adults fly to the plant and repeat the cycle. There may be 12-15 generations per year with the entire cycle from egg to adult requiring less than 16 days in warm weather.
Thrips Control: Remove weeds and grass from around garden areas to eliminate alternate hosts. Yellow sticky traps are helpful for monitoring adult populations. If found, use the Bug Blaster or hose off plants with a strong stream of water to reduce pest numbers. Release commercially available beneficial insects, such as Minute Pirate Bugs, Thrips Predators, ladybugs and lacewing, to attack and destroy all stages of thrips. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap, neem oil, and botanical insecticides can be used to spot treat heavily infested areas. Clean up crop debris, especially onion leaves after harvest.
Tip: Insecticidal soap, neem oil, and botanical insecticides are contact insecticides. For effective control, it is necessary to provide thorough coverage, especially inside the plant base of the leaves where the majority of pests are located.
Photo Credit: Jack Kelly Clark
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Whitefly Control
Description: Common on houseplants and in greenhouses, the whitefly (Trialeurodes vaporariorum) is a sap-sucking insect that is often found in thick crowds on the undersides of leaves. When infested plants are disturbed, great clouds of the winged adults fly into the air. Both nymphs and adults damage plants by sucking the juices from new growth causing stunted growth, leaf yellowing, and reduced yields. Plants become weak and susceptible to disease.
Like aphids, whiteflies secrete honeydew, so leaves maybe sticky or covered with a black sooty mold. They are also responsible for transmitting several plant viruses. In southern and coastal states, this pest will be found year-round in outdoor gardens. In northern areas year-round infestations are possible only indoors. Host plants include more than 250 ornamental and vegetable plants. Citrus, squash, poinsettia, potato, cucumber, grape, tomato, and hibiscus are commonly infested.
Whitefly adults (1/16 inch long) are moth-like insects with powdery white wings and short antenna. They are easily recognized and often found near the tops of plants or on stem ends. Wingless nymphs are flattened, oval and almost scale-like in appearance. After the first instar, or crawler stage, they settle down and attach themselves to the underside of leaves and begin feeding.
Life Cycle: Whitefly nymphs overwinter on the leaves of host plants. In late spring adult females deposit 200-400 eggs in circular clusters on the undersides of upper leaves. The eggs hatch in 5-10 days and first instar nymphs, which resemble small mealybugs and are called crawlers, move a short distance from the egg before flattening themselves against the leaf to feed. The remaining nymphal stages (2nd, 3rd and 4th) do not move. A non-feeding pupal stage follows and within a week, young adults emerge to repeat the cycle. There are many generations per year. Whiteflies develop from egg to adult in approximately 25 days at room temperature. Adults may live for one to two months.
Note: All of the immature stages are easily overlooked. They are usually pale, almost translucent, and blend with the color of the leaf to which they are attached. Superficially they are similar to several scale insects.
Whitefly Control: Yellow sticky traps are helpful for monitoring and suppressing adult populations. If found, use the Bug Blaster or hose off plants with a strong stream of water to reduce pest numbers. Natural predators of this pest include ladybugs and lacewing, which feed on their eggs and the whitefly parasite which destroys nymphs and pupae. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap, neem oil, and botanical insecticides can be used to spot treat heavily infested areas. Spot treat with insecticidal soap or botanical insecticides if population become intolerable.
Tip: Insecticidal control can be difficult because the insect is resistant to many synthetic insecticides. However, horticultural oils, which work by smothering insects, are very effective on all stages of this pest.
Note: Ants feed on the honeydew that sucking insects produce and will protect these pests from their natural enemies. An application of Tanglefoot Pest Barrier to the stalks of roses and other woody plants will help keep ants away.
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Flea Beetle Control
Description: Many species of flea beetles are found throughout the United States. They are small jumping insects (similar in appearance to fleas) commonly found in home gardens early in the growing season. A voracious pest, they will damage plants by chewing numerous small holes in the leaves, which make them look as if they have been peppered by fine buckshot. When populations are high, flea beetles can quickly defoliate and kill entire plants. They feed most on hot sunny days and attack a wide variety of plants including beans, cabbage, corn, eggplant, potatoes, peppers, tomatoes, lettuce, and most seedlings.
Adults are small (1/10 inch long), shiny, dark brown or black beetles with large hind legs that allow them to jump when disturbed. Some species may have white or yellow stripes on their wing cases. Larvae are small, cream-colored worms (1/8 - 1/3 inch long). They live underground and feed on the roots and tubers of young plants as well as on germinating seeds.
Note: Flea beetles transmit viral and bacterial diseases.
Life Cycle: Adults overwinter in the soil or garden debris and become active in the spring, feeding on host plants as new growth appears. Tiny white eggs are laid on or in soil cracks around the base of plants. These hatch in about one week, and the slender white larvae feed on plant roots for approximately 2-3 weeks. Pupae usually remain in the soil for 7-9 days until adults emerge and the cycle is completed. There are one to four generations per year, depending on species and climate.
Flea Beetle Control: Remove garden trash and plow or roto-till under weeds to reduce overwintering sites. Floating row covers are extremely effective when placed on seedlings and left in place until plants are old enough to tolerate beetle damage. Place yellow sticky traps throughout garden rows every 15 to 30 feet to capture adults. Beneficial nematodes applied to the soil will destroy the larval stage, reducing root feeding and helping to prevent the next generation of adults from emerging. Diatomaceous earth can be dusted over plants to control the number of feeding adults. If pest populations become intolerable, spot treat with botanical insecticides as a last resort.
Tip: Trap crops, such as mustard and radish, can be planted near garden areas to draw pests away.
Photo Credit: Lee Jenkins
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Armyworm Control
Description: The armyworm gets its name because it travels in small insect armies and consumes just about everything in its path. Armyworm caterpillars (1-3/4 inch long) are most active at night and hide under garden debris during the day. They skeletonize leaves of lettuce, cole crops, beans, and corn. In tomatoes they make shallow gouges in fruit.
Markings on newly hatched caterpillars are usually hard to distinguish, older larvae have distinctive stripes that run the entire length of the body. Fall armyworms (Spodoptera frugiperda) are brown with yellow stripes, beet armyworms (Spodoptera exigua) are green with light stripes. Adults are gray, mottled moths (1-1/2 inch wingspan) with a small white dot in the center of each forewing and dark margins on the hind wings.
Life Cycle: Armyworm eggs are laid in fluffy masses on crowns of seedlings and on leaves of older plants. In 5-10 days tiny caterpillars hatch and begin feeding for several weeks. They then pupate and emerge as adults 10 days later. One to six generations per year. Some armyworm species overwinter as caterpillars in the soil, other species migrate south.
Armyworm Control: Outbreaks of this pest are not common because they have many natural predators. Use pheromone traps to determine the main flight period for moths, then release trichogramma wasps to parasitize the newly laid eggs. Beneficial insects, such as lacewing, ladybugs, and minute pirate bugs feed on armyworm eggs, as well as the young larval stage.
Monitor plants closely in early spring or summer months for signs of insect damage. Caterpillars will often be found feeding on the undersides of leaves and on new growth. Handpick pests that are discovered and drop them in a bucket of soapy water. Applications of Dipel Dust (Bt-kurstaki) or Monterey Garden Insect Spray (spinosad) will also kill caterpillars. Use botanical insecticides if pest levels become intolerable.
Photo Credit: Jack Kelly Clark
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Root Maggot Control
Description: Many species of the root maggot exist in home gardens throughout North America. Particularly destructive to early season plantings, they feed underground on succulent roots and attack a large variety of vegetable crops including radish, cabbage, carrot, turnip, and onions. Heavily infested roots are often riddles with tunnels and rotted. Affected plants lack vigor, may be stunted or yellowed, and often wilt during the heat of the day. In some cases, maggots may even chew through taproots, causing plants to die.
Adults (1/5 inch long) are dark gray flies that look like the common housefly, only smaller. They lay their eggs in the soil at the base of host plants and are very good at detecting newly planted seed beds. Maggots (1/3 - 1/4 inch long) are small, yellowish white, legless larvae with tapered or pointed heads and a rear end that is blunt.
Note: Tunneling and feeding by this pest creates entry points for rot diseases such as black rot.
Life Cycle: Adults emerge in the spring or early summer from overwintering pupal cocoons in the soil. They soon mate and females begin depositing 50-200 small, white eggs in plant stems right at the soil line or in cracks in the soil near plant stems. Eggs hatch in a few days and the larvae burrow down into the soil to feed on small roots, root hairs, and germinating seeds. After feeding for 1-3 weeks, maggots begin to pupate in plant roots or the surrounding soil. There are several generations per year.
Root Maggot Control: Female flies are attracted for egg laying by the moisture emitted from newly planted seed rows. Cover seedbeds with floating row covers immediately after seeds are sown to prevent infestation. Be sure the cover extends at least 6 inches on each side of the seed rows. Heavy paper collars or other sturdy material may be placed around the base of transplants to prevent egg laying around stems. Applying beneficial nematodes in seed furrows or as a top dressing around plants can be effective in controlling the larvae. Roto-till under crop debris immediately after harvest to destroy overwintering sites.
Photo Credit: Jack Kelly Clark
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One bug does not make a problem! In nature, there are always some garden pests chewing on plants; that's just the way it is. However, not all pest damage is significant enough to warrant action. Even the healthiest gardens encounter bugs at one time or another, yet they still produce a beautiful harvest. As gardeners, we must each consider the level of pest activity that we are willing to tolerate.
The best way to maintain a healthy garden is to educate yourself and learn to identify common "bad bugs." Inspect your garden regularly to detect problems early. The sooner a pest is identified the easier it will be to manage using earth-friendly methods. Below we've listed several garden invaders that you may encounter. Click on each pest picture for a description and our list of organic remedies.
Ant
Where: Pestiferous in gardens where they protect aphids and other pest insects.
Aphids
Where: In clusters under leaves and on new growth.
Armyworm
Where: Leaves of lettuce, cole crops, beans, tomatoes and corn.
Asparagus Beetle
Where: One of the most destructive pests of asparagus.
Cabbage Looper
Where: Leaves of cabbage-family plants.
Cabbageworm
Where: Chews irregular holes in leaves (primarily cole crops).
Chinch Bug
Where: On corn and sorghums, also injures small grains and other grass crops.
Colorado Potato Beetle
Where: Leaves of potatoes, tomatoes, and eggplants.
Corn Earworm
Where: One of the most destructive insect pests attacking corn. Also found on cotton and tomatoes.
Cucumber Beetle
Where: Leaves, flowers, and fruits of cucumbers, squash, pumpkins, melons, and other plants.
Cutworm
Where: At night, cutworms clip off seedling stems near or just below the soil surface.
Earwig
Where: Leaves, flowers and shoots of most vegetables, flowers and ornamentals.
European Corn Borer
Where: Leaves, tassels and stalks of corn; also found on peppers, snap beans, potatoes, tomatoes and apples.
Flea Beetle
Where: Chews numerous small holes in the leaves of many crops. Jumps like a flea.
Grasshopper
Where: One of the most destructive insect pests attacking gardens and landscapes.
Leafhopper
Where: Found on a variety of fruit and vegetable crops.
Mexican Bean Beetle
Where: On the underside of the leaves of all bean varieties.
Psyllid
Where: On a variety of plants, including most fruit trees and small fruits, as well as tomato and potato.
Root Maggot
Where: Underground where they attack many vegetable crops including radish, carrot, turnip, and onions.
Slug & Snail
Where: Throughout the United States on a variety of plants as well as on decaying plant material.
Sowbug (Pillbug)
Where: On decaying matter; occasionally on seedlings, new roots and lower leaves.
Spider Mite
Where: In colonies, mostly on the underside of leaves.
Squash Bug
Where: Throughout North America on the leaves and stems of squash and pumpkins.
Thrips
Where: Leaves, fruits and flowers of many plants.
Tomato Hornworm
Where: The most destructive and widely distributed pest of tobacco and tomato plants.
Whitefly
Where: Leaves, flowers and fruits of many vegetable and ornamental plantings.
Wireworm
Where: Underground attacking germinating seeds, roots, and tubers of plants.
Aphid Control
Description: There are approximately 4,000 aphid species found throughout the world. A common pest on many garden vegetables, fruit trees and ornamental plants, these sap-sucking insects are often noticed feeding in clusters or colonies under leaves and on new succulent shoots. Low to moderate numbers are usually not harmful, but heavy infestations may cause leaves to curl, wilting, yellowing, and stunted growth, as well as a general decline in overall plant vigor. Several species will also transmit a number of plant diseases, particularly viruses which they transmit during feeding.
Aphids are small (1/8 inch long), soft bodied, pear-shaped insects that may be green, yellow, brown, red or black in color depending on species and food source. Generally adults are wingless, but some can grow wings, especially if populations are high. They have two whip-like antennae at the tip of the head and a pair of tube-like structures, called cornicles, projecting backward out of their hind end.
Note: As they feed, aphids secrete large amounts of a sticky fluid known as honeydew. This sweet goo drips onto plants, attracting ants and promoting a black sooty mold growth on leaves. Cars and lawn furniture that are under infested trees will also be covered with this sticky fluid.
Life Cycle: In spring wingless female aphids hatch from overwintering eggs and soon give birth to many nymphs (males are not present). Young nymphs increase gradually in size and within a week give birth to many more nymphs. This process is repeated several times and results in huge population explosions. As the colony grows, a few of the females develop wings and fly off to other host plants to start new colonies. In late summer and early fall sexual forms (males and females) develop which mate and lay overwintering eggs. There are many overlapping generations per year.
Note: Most aphids, except for the sexual forms, do not have to mate in order to reproduce, and they produce live young, rather than eggs.
Control: Pinch or prune off heavily infested leaves or other plant parts. Use the Bug Blaster or hose off plants with a strong stream of water to reduce pest numbers. Commercially available beneficial insects, such as ladybugs and lacewing are important natural predators. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas. Horticultural oils should be applied early in the season or late in the fall to destroy overwintering eggs.
Tip: Do not over water or over fertilize - aphids like plants with high nitrogen levels and soft new growth. Try organic fertilizers which release nutrients slowly.
Note: Ants feed on the honeydew that sucking insects produce and will protect these pests from their natural enemies. An application of Tanglefoot Pest Barrier to the stalks of roses and other woody plants will help keep ants away.
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Spider Mite Control
Description: Common across North America, many species of the spider mite (family: Tetranychidae) attack both indoor and outdoor gardens and can be very destructive in greenhouses. They live in colonies, mostly on the underside of leaves and feed by piercing leaf tissue and sucking up the plant fluids. Feeding marks show up as light dots on the leaves; as feeding continues, the leaves turn yellow, and may dry up and drop off. Spider mites are most common in hot, dry conditions and when their natural enemies have been killed off by insecticide use. They are also very prolific, which is why heavy infestations often build up unnoticed before plants begin to show damage. Large populations may be accompanied by fine webbing. Host plants are many and include strawberries, melons, beans, tomatoes, eggplant, ornamental flowers, trees and most houseplants.
Spider mites are not true insects, but are classed as a type of arachnid, relatives of insects that also includes spiders, ticks, and scorpions. Adults are reddish brown or pale in color, oval-shaped, and very small (1/50 inch long) - about the size of the period at the end of this sentence. Immature stages resemble the adults except only smaller.
Life Cycle: Most spider mite species overwinter as eggs on the leaves and bark of host plants. In early spring, as temperatures warm, tiny six-legged larvae begin hatching and feed for a few days before seeking shelter where they molt into the first nymphal stage. Nymphs have eight-legs and pass through two more molts before becoming mature adults. After mating, females are capable of producing as many as 300 eggs over a couple of weeks. Hot, dry weather favors rapid development of these pests. During such conditions the time it takes to pass from egg to adult may occur in as little as 5 days. There are several overlapping generations per year.
Note: Dispersal over a wide area occurs when spider mites are carried on their webbing by the wind.
Control: If pests are found, pinch or prune off infested leaves or other plant parts. Use the Bug Blaster or wash plants with a strong stream of water to reduce pest numbers. Commercially available beneficial insects, such as ladybugs, lacewing, and predatory mites are important natural enemies. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas. Horticultural oils should be applied early in the season or late in the fall to destroy overwintering eggs.
Tip: Control strategies must take into account the fast development time of this pest, especially during warm weather when eggs are laid continuously. Just targeting the adults will do little good - repeat treatments are almost always necessary.
Photo Credit: Jack Kelly Clark
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Doktor Doom Insect Fogger
Thrips Control
Description: There are more than 6,000 thrips species known in the world. A common pest found in greenhouses, and ornamental and vegetable gardens, they damage plants by sucking their juices, and scraping at fruits, flowers and leaves. Leaves may turn pale, splotchy and silvery, then die. Injured plants are twisted, discolored and scarred. Extremely active, thrips feed in large groups and leap or fly away when disturbed. Host plants include onions, beans, carrots, squash and many other garden vegetables and many flowers, especially gladioli and roses.
Adults are very small (less than 1/25 inch) straw-colored or black slender insects with two pairs of feathery wings. Without the use of a hand lens, they resemble tiny dark threads. Both adults and the wingless larvae are attracted to white, yellow and other light colored blossoms and are responsible for spreading tomato spotted wilt virus and impatiens necrotic spot virus.
Life Cycle: Adults and pupae overwinter in garden soil. In spring, newly emerged females insert eggs into the tissues of flowers, leaves or stems. (They do not need to mate for reproduction.) Each female can produce up to 80 eggs, which hatch within days in warm weather, or weeks to months in colder weather. They become wingless larvae (nymphs), which feed on plant sap. After two or more nymphal stages, many thrips drop to the soil to pupate. Emerging adults fly to the plant and repeat the cycle. There may be 12-15 generations per year with the entire cycle from egg to adult requiring less than 16 days in warm weather.
Thrips Control: Remove weeds and grass from around garden areas to eliminate alternate hosts. Yellow sticky traps are helpful for monitoring adult populations. If found, use the Bug Blaster or hose off plants with a strong stream of water to reduce pest numbers. Release commercially available beneficial insects, such as Minute Pirate Bugs, Thrips Predators, ladybugs and lacewing, to attack and destroy all stages of thrips. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap, neem oil, and botanical insecticides can be used to spot treat heavily infested areas. Clean up crop debris, especially onion leaves after harvest.
Tip: Insecticidal soap, neem oil, and botanical insecticides are contact insecticides. For effective control, it is necessary to provide thorough coverage, especially inside the plant base of the leaves where the majority of pests are located.
Photo Credit: Jack Kelly Clark
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Whitefly Control
Description: Common on houseplants and in greenhouses, the whitefly (Trialeurodes vaporariorum) is a sap-sucking insect that is often found in thick crowds on the undersides of leaves. When infested plants are disturbed, great clouds of the winged adults fly into the air. Both nymphs and adults damage plants by sucking the juices from new growth causing stunted growth, leaf yellowing, and reduced yields. Plants become weak and susceptible to disease.
Like aphids, whiteflies secrete honeydew, so leaves maybe sticky or covered with a black sooty mold. They are also responsible for transmitting several plant viruses. In southern and coastal states, this pest will be found year-round in outdoor gardens. In northern areas year-round infestations are possible only indoors. Host plants include more than 250 ornamental and vegetable plants. Citrus, squash, poinsettia, potato, cucumber, grape, tomato, and hibiscus are commonly infested.
Whitefly adults (1/16 inch long) are moth-like insects with powdery white wings and short antenna. They are easily recognized and often found near the tops of plants or on stem ends. Wingless nymphs are flattened, oval and almost scale-like in appearance. After the first instar, or crawler stage, they settle down and attach themselves to the underside of leaves and begin feeding.
Life Cycle: Whitefly nymphs overwinter on the leaves of host plants. In late spring adult females deposit 200-400 eggs in circular clusters on the undersides of upper leaves. The eggs hatch in 5-10 days and first instar nymphs, which resemble small mealybugs and are called crawlers, move a short distance from the egg before flattening themselves against the leaf to feed. The remaining nymphal stages (2nd, 3rd and 4th) do not move. A non-feeding pupal stage follows and within a week, young adults emerge to repeat the cycle. There are many generations per year. Whiteflies develop from egg to adult in approximately 25 days at room temperature. Adults may live for one to two months.
Note: All of the immature stages are easily overlooked. They are usually pale, almost translucent, and blend with the color of the leaf to which they are attached. Superficially they are similar to several scale insects.
Whitefly Control: Yellow sticky traps are helpful for monitoring and suppressing adult populations. If found, use the Bug Blaster or hose off plants with a strong stream of water to reduce pest numbers. Natural predators of this pest include ladybugs and lacewing, which feed on their eggs and the whitefly parasite which destroys nymphs and pupae. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap, neem oil, and botanical insecticides can be used to spot treat heavily infested areas. Spot treat with insecticidal soap or botanical insecticides if population become intolerable.
Tip: Insecticidal control can be difficult because the insect is resistant to many synthetic insecticides. However, horticultural oils, which work by smothering insects, are very effective on all stages of this pest.
Note: Ants feed on the honeydew that sucking insects produce and will protect these pests from their natural enemies. An application of Tanglefoot Pest Barrier to the stalks of roses and other woody plants will help keep ants away.
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Flea Beetle Control
Description: Many species of flea beetles are found throughout the United States. They are small jumping insects (similar in appearance to fleas) commonly found in home gardens early in the growing season. A voracious pest, they will damage plants by chewing numerous small holes in the leaves, which make them look as if they have been peppered by fine buckshot. When populations are high, flea beetles can quickly defoliate and kill entire plants. They feed most on hot sunny days and attack a wide variety of plants including beans, cabbage, corn, eggplant, potatoes, peppers, tomatoes, lettuce, and most seedlings.
Adults are small (1/10 inch long), shiny, dark brown or black beetles with large hind legs that allow them to jump when disturbed. Some species may have white or yellow stripes on their wing cases. Larvae are small, cream-colored worms (1/8 - 1/3 inch long). They live underground and feed on the roots and tubers of young plants as well as on germinating seeds.
Note: Flea beetles transmit viral and bacterial diseases.
Life Cycle: Adults overwinter in the soil or garden debris and become active in the spring, feeding on host plants as new growth appears. Tiny white eggs are laid on or in soil cracks around the base of plants. These hatch in about one week, and the slender white larvae feed on plant roots for approximately 2-3 weeks. Pupae usually remain in the soil for 7-9 days until adults emerge and the cycle is completed. There are one to four generations per year, depending on species and climate.
Flea Beetle Control: Remove garden trash and plow or roto-till under weeds to reduce overwintering sites. Floating row covers are extremely effective when placed on seedlings and left in place until plants are old enough to tolerate beetle damage. Place yellow sticky traps throughout garden rows every 15 to 30 feet to capture adults. Beneficial nematodes applied to the soil will destroy the larval stage, reducing root feeding and helping to prevent the next generation of adults from emerging. Diatomaceous earth can be dusted over plants to control the number of feeding adults. If pest populations become intolerable, spot treat with botanical insecticides as a last resort.
Tip: Trap crops, such as mustard and radish, can be planted near garden areas to draw pests away.
Photo Credit: Lee Jenkins
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Armyworm Control
Description: The armyworm gets its name because it travels in small insect armies and consumes just about everything in its path. Armyworm caterpillars (1-3/4 inch long) are most active at night and hide under garden debris during the day. They skeletonize leaves of lettuce, cole crops, beans, and corn. In tomatoes they make shallow gouges in fruit.
Markings on newly hatched caterpillars are usually hard to distinguish, older larvae have distinctive stripes that run the entire length of the body. Fall armyworms (Spodoptera frugiperda) are brown with yellow stripes, beet armyworms (Spodoptera exigua) are green with light stripes. Adults are gray, mottled moths (1-1/2 inch wingspan) with a small white dot in the center of each forewing and dark margins on the hind wings.
Life Cycle: Armyworm eggs are laid in fluffy masses on crowns of seedlings and on leaves of older plants. In 5-10 days tiny caterpillars hatch and begin feeding for several weeks. They then pupate and emerge as adults 10 days later. One to six generations per year. Some armyworm species overwinter as caterpillars in the soil, other species migrate south.
Armyworm Control: Outbreaks of this pest are not common because they have many natural predators. Use pheromone traps to determine the main flight period for moths, then release trichogramma wasps to parasitize the newly laid eggs. Beneficial insects, such as lacewing, ladybugs, and minute pirate bugs feed on armyworm eggs, as well as the young larval stage.
Monitor plants closely in early spring or summer months for signs of insect damage. Caterpillars will often be found feeding on the undersides of leaves and on new growth. Handpick pests that are discovered and drop them in a bucket of soapy water. Applications of Dipel Dust (Bt-kurstaki) or Monterey Garden Insect Spray (spinosad) will also kill caterpillars. Use botanical insecticides if pest levels become intolerable.
Photo Credit: Jack Kelly Clark
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Root Maggot Control
Description: Many species of the root maggot exist in home gardens throughout North America. Particularly destructive to early season plantings, they feed underground on succulent roots and attack a large variety of vegetable crops including radish, cabbage, carrot, turnip, and onions. Heavily infested roots are often riddles with tunnels and rotted. Affected plants lack vigor, may be stunted or yellowed, and often wilt during the heat of the day. In some cases, maggots may even chew through taproots, causing plants to die.
Adults (1/5 inch long) are dark gray flies that look like the common housefly, only smaller. They lay their eggs in the soil at the base of host plants and are very good at detecting newly planted seed beds. Maggots (1/3 - 1/4 inch long) are small, yellowish white, legless larvae with tapered or pointed heads and a rear end that is blunt.
Note: Tunneling and feeding by this pest creates entry points for rot diseases such as black rot.
Life Cycle: Adults emerge in the spring or early summer from overwintering pupal cocoons in the soil. They soon mate and females begin depositing 50-200 small, white eggs in plant stems right at the soil line or in cracks in the soil near plant stems. Eggs hatch in a few days and the larvae burrow down into the soil to feed on small roots, root hairs, and germinating seeds. After feeding for 1-3 weeks, maggots begin to pupate in plant roots or the surrounding soil. There are several generations per year.
Root Maggot Control: Female flies are attracted for egg laying by the moisture emitted from newly planted seed rows. Cover seedbeds with floating row covers immediately after seeds are sown to prevent infestation. Be sure the cover extends at least 6 inches on each side of the seed rows. Heavy paper collars or other sturdy material may be placed around the base of transplants to prevent egg laying around stems. Applying beneficial nematodes in seed furrows or as a top dressing around plants can be effective in controlling the larvae. Roto-till under crop debris immediately after harvest to destroy overwintering sites.
Photo Credit: Jack Kelly Clark
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