A pest insect or bug is one that is detrimental, invasive, troublesome, or causes a nuisance to other plants and animals.

Pest insects and bugs are not welcome in your garden, they are the ones you will want to keep under control or get rid of completely.  Below you will find a list of these insects and bugs.  Also, a description of each and directions on how to control them.

Whitefly (Aleyrodidae)

White flies on a stem.
Silverleaf Whitefly

This pest insect is found throughout the United States.  Whiteflies are soft-bodied, winged insects closely related to aphids and mealybugs.  Being as small as 1/2 inch and somewhat triangular in shape and can usually be found on the undersides of leaves.  The tiny insects feed in large numbers by sucking plant juices from the leaves and stems of many plants.  Whiteflies secrete a sticky, sugary substance called honeydew that may cause the growth of a sooty black fungus on the leaves.  Eggs laid on leaf undersides hatch into tiny larvae that look like flat, oval semitransparent scales.

The larvae reach adulthood within about a month of hatching.

Remember to check any new plants for whiteflies before you purchase them.  Although, they are hard to spot, whiteflies are active during the day, so this helps when trying to find them.

Plants attacked by Whiteflies

  • Cucumbers
  • Lettuce
  • Flowers
  • Tomatoes
  • Trees
  • Shrubs


Aphids (Aphidoidea)

A brown aphid insect on a leaf with water droplets around it.

Aphids are pest insects found throughout the United States.  You might know the aphid by some other common names such as greenfly, and blackfly.  As the name suggests, each species can vary widely in color.

These small, sap-sucking, soft-bodied insects may be green, pink, black, or yellow, depending on the species.

Some stages of the life cycle are winged, others are wingless.  Adult aphids and numphs (young aphids) look alike except in size.

The best way to check for aphids is to look for the presence of two tail pipes (cornicles) found at the end of their abdomen.

Aphids feed on a wide variety of plants, including edible and ornamental plants and can be found on indoor and outdoor plants.

They can be found clustering on tips of new growth and leaf undersides, sucking out the juices and causing the leaves to become distorted and turn yellow.  Aphids can cause the plant to a become weak, stunted or have poor plant growth.

Aphids secrete a sugary fluid called honeydew that attracts ants and may cause the growth of a sooty black fungus on leaves.

In small number aphids do little damage, but they reproduce rapidly and can also spread disease among plants.

Controlling Aphids
Green aphid insect on a white flower
Green Aphid
  1. Remove weeds from your garden to reduce potential sites for aphids.  The weeds can support large numbers of aphids, by removing them you reduce their chances of survival.
  2. Aphids can grow faster on excess nitrogen.  So, by applying less soluble forms of nitrogen in small portions, throughout the season, you will keep aphid growth under control.
  3. You can spray aphids with water from a garden hose and knock them off the plants.  This can also help wash off any honeydew and sooty mold that may be present.
  4. When found in small numbers they can be crushed.
  5. Pesticides can be used to control aphids but whenever using any pesticide, choose low impact, natural or organic pesticides and always follow the directions and use safety precautions.  Pesticides such as Neem (azadirachtin) is a plant-based pesticide that discourages aphid feeding causing the aphids to slowly die.
  6. Insecticidal soap, horticultural oil and pyrethrum are also very effective at controlling aphids
Natural predators include:


Mealybugs (Pseudococcidae)

Mealy Bug

Several species of Mealy bugs pose problems for gardeners across North America.  They can be found in moist, warm climates.  Mealybugs are pink, oval in shape, soft-bodied insects covered with a white waxy, cottony material that serves as a protective coating.  Females are rounded, wingless and about 1/16 inch long.  If you see fluffy-looking white blobs on your plants, indoor or out, you probably have mealybugs.

Host plants include:
  • Apples
  • Citrus
  • Grapes
  • Peaches
  • Potatoes
  • Tropical plants-including in-door houseplants.

These tiny pest insects and bugs appear in clusters on the underside of leaves and clumped in the forks of twigs and branches where they suck plant juices.

As they feed, some species inject toxins that damage plant tissue.

Large clumps of mealybugs may resemble fur or lint attached to a plant.  Symptoms of their presence include yellowing leaves and dark dirty patches on leaves, which is a sooty mold growing on the sweet mealybug excretion called honeydew.  They can also cause wilting and general plant decline sometimes leading to death.

Pests insects overwinter as eggs in cottony egg sacs or as tiny nymphs (the juvenile stage, commonly called crawlers).

In regions without freezing mealybugs are present year-round.  Colder climates may see two to three generations per year.

Controlling Mealybugs
  1. Chemical controls can be used to treat mealybugs.  Less toxic alternatives such as insecticidal soap or horticultural oils can be effective but must be applied to the hard to reach places the mealybugs inhabit to kill the insects.  These may require several applications to achieve control.
  2. Pruning heavily infested plant parts.  Be sure to dispose of plant parts immediately since mealybugs can survive on the detached part, as long as it has moisture.
  3. With severe mealybug infestations removing and replacing with a healthy plant is the best way to control them.
  4. You can try washing them off with water or using a cotton swab dipped in alcohol.  This works best when you have a small infestation and may not get all the mealybugs off plants.
  5. Some natural enemies include parasitic wasps, and lady beetles.


Scale (Icerya purchase)

cottony Scale garden insects and bugs. Feeding on a stem.
Cottony Cushion Scale

Scale pest insects can be found throughout the United States.

Scale insects attack various kinds of fruits and ornamental plants, as well as house plants, by attaching themselves to branches, twigs, and the undersides of leaves.  Appearing as small bumps scale insects suck sap from plants, robbing them of essential nutrients.

They thrive in warm, dry places.  Some species of scale are small, oval and flattened with a protective tan to brown shell-like covering.  While others, such as cottony cushion scale is thick, white and covered with a waxy or wooly substance.

Leaves on infested plants turn yellow and the overall vigor of the plant declines.  Severely infested plants may die after several seasons.

Mature females feed, lay eggs, and raise families under their protective shell.  Eggs hatch into crawlers that feed by sucking plant juices.  As they mature, crawlers produce a shell-like covering and lose their legs.

There may be several generations per year.

Controlling Scale
  1. One possibility is to pick off or gently scrub them loose from the leaves or stems.  Dabbing each scale with an alcohol-soaked cotton swab is another possibility for lightly infested plants.
  2. You can use chemical products like the insecticide spray, neem oil, available at garden centers.
  3. For heavy infestation, it is sometimes best to throw away the plants.
  4. Insecticidal soap is a safe and effective alternative and can be prepared at home with bleach-free dishwashing soap )1 1/2 teaspoon per quart of water) and water.
  5. An oil spray can be used as well and prepared by mixing 2 tablespoons of cooking oil and 2 tablespoons of baby shampoo in one gallon of water.  This can also be mixed with 1 cup of alcohol to help penetrate the insect’s shell.  If fungus is also present, add 2 tablespoons of baking soda.  Shake well before applying.  Spray every five to seven days as needed.  Coat the leaves well.
  6. Always test your home remedies on a small portion of the plant first to make sure it won’t harm the plant.  Also, never use bleach-based soaps.  Do not spray on hairy or waxy-leaved plants.  And do not apply to any plants on a hot or brightly sunny day as this will lead to burning the plant and death.


Spider mites(Tetranychidae)

Red spider mites
Red Spider Mites

Spider mites belong to the Acari family Tetranychidae, which include about 1200 species.  Adult spider mites are about 0.4 mm long and have eight legs, can be pale yellow to green or orange to brown.  Females lay between 50-100 eggs in their lifetime.

Also known as mites, they feed on many different plants.  The eggs are laid on the undersides of leaves in dense colonies where they spin a protective silk webs, and cause damage to plants by puncturing the plants cell to feed.

The larva hatch after the last frost and have six legs.  Little feeding is done at this stage.

Symptoms of their feeding show up as slivering, or stippling-effect on the leaf top.  More severe damage can result in leaf yellowing and leaf dropping.  Additional signs include curled and burned leaf edges and leaves that have taken on a leathery texture.  Although symptoms can vary with different plants.

On the underside of an effected leaf you are likely to find spider mite webbing.  If you rub the leaf it will feel gritty.

Mites feed on many kinds of plants, including edibles and ornamentals, with houseplants being their favorite target.

Controlling Spider Mites
Spotted spider mite. Translucent white.
Spotted Spider Mite
  1. Keep a sanitized environment and inspect plant for mites before planting.
  2. Keep plants well-watered and fed to keep stress on plants to a minimum.
  3. Insecticides such as sprays like Neem oil, Pyrethrin, Azadirachtin, and Horticultural oil.  They can be sprayed directly on the spider mites, larvae, nymphs and eggs to kill on contact.
  4. Beneficial insects as natural predators.  These include Ladybugs, Assassin bugs, green lacewing, and minute pirate bug.  Attract these insects and bugs or purchase them commercially.   Purchase  beneficial insects and bugs here.



Thrips (Thysanoptera)

Thrips are minute, shiny, elongated blackish or yellowish slender insects with fringed wings and unique asymmetrical mouthparts.  Although the adults have feathery fringed wings the nymphs are wingless.

Without a magnifying glass you probably won’t be able to see thrips on your plants, but you may notice sign of thrips presence.  Some signs include black, shiny speckles (droppings), slivering, stippling (masses of tiny discolored scars on plant parts), or in severe cases, deformed growth.

Thrips prefer to feed on new, rapidly growing plant tissue where it is easy to hide.  Most of the time thrips cause only slight damage, but masses of thrip can be quite destructive.

Feeding thrips can prevent rose buds from opening and results in deformed petals.

Certain species can spread viruses to tomatoes and impatiens.

Thrip usually attack garden plants including:

  • Asparagus
  • Cabbage
  • Lettuce
  • Onions
  • Peas
  • Flowers
  • Fruit trees
  • Shade trees
  • Tomatoes
  • Impatiens
  • Gladioli
  • Roses

There can be many generations per year depending on the climate.

Controlling Thrip
  1. Clean up any garden debris, weeds, and grass from around your garden area so you eliminate alternate host for the thrip.
  2. Be sure to examine any new plants going into the garden.  Discard any infested plants by bagging and putting in the trash.
  3. You can reduce pest numbers by spraying plant with a strong spray of water that knocks them off the plant.
  4. Purchase and release commercially available beneficial insects such as Minute Pirate bugs, ladybugs, and lacewing.  Before releasing any beneficial insects, you should first use the strong spray of water to knock down the infestation of thrip.
  5. The insecticide pyrethrin can be used to reduce numbers.  Then follow up with the predatory insects.
  6. Insecticidal soap can be used.  It is effective in knocking out infestations and is not harmful to most beneficial insects but will kill the pest insects and bugs.
  7. Spinosad and neem oil can be used to spot treat heavily infested areas.  Thorough coverage is necessary, especially on the undersides of leaves and where leaves attach to stems.  These are the areas thrip are most likely to be found in.



Leaf Minor

The most commonly known species of the leaf minor is the larvae of tiny black flies.  The mature larvae tunnel between the upper and lower layer of leaf tissue creating visible trails or miner in the process.  They will then cut a hole through the leaf and drop to the ground to pupate.  It emerges two to three weeks later as a tiny black fly.

Adult flies lay eggs on the undersides of leaves.  After hatching, the life cycle starts over when the larvae tunnel into leaves to feed.  The leaf miner gains some protection from other predators when in between layers.

Many weeds serve as hosts, including lambs-quarter, pigweed, henbane, and nightshade.

Leaf minors are pest  insects and bugs that attack many plants including:

  • Beets
  • Chard
  • Lettuce
  • Peppers
  • Potatoes
  • Spinach
Controlling Leaf Minors
  1. Early detection is important.  Check leaves on young seedlings.  If you find any signs of small white eggs, mines or hatching larvae you should remove the leaf and discard in trash.  If plant is highly infested removal of the plant and discarding it is probably the best chance to protect other plants in the garden.
  2. A common method to rid plants of leaf minors is to spray the plant with pesticides.  But, with pesticides you must spray at the right time.  To determine the right time, take a few infected leaves and put them in a zip-lock baggie.  Check the bag daily and when you see small black flies in the bag it is time to spray plants daily for a week.
  3. Beneficial insects and bugs can be bought commercially and released into the garden.  When released, the beneficial insects and bugs will kill the pest insect and bugs.
  4. Clean any weeds and garden debris from the garden area.  These are the perfect hosts for leaf minors.
  5. Tilling the soil in early spring will kill the overwintering pupae.

For a complete guide to other insects and bugs in the garden get your guide below.

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I hope you found the information here helpful and informative.  Knowing which insects and bugs are determental to your garden can help you to spot, control, and destroy them before they cause any damage to your plants.  Healthy plants equal a productive garden!

Happy Gardening,


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