Insect Resources

Armyworms can be problematic pests in cereal grains. Armyworms are moth caterpillars that vary in color (gray or green) with a distinct yellow, white, and brown strip along the body. The adult is a yellow-brown moth. Moths emerge in spring months and lay eggs on wheat or barley. Larvae developing from these eggs then feed on wheat from May into the summer.

Aphids can be problematic pests in wheat. There are several species of aphids in wheat fields. These include the English grain aphid and the bird-cherry oat aphid. Different species have different life cycles. Aphids do little direct damage to wheat plants but can be problematic due to transmission of viruses.

The cereal leaf beetle can be a problematic pest in cereal. Cereal leaf beetles overwinter and emerge in the spring, where they can move into winter and then spring wheat. Larvae and adults can do significant damage to crops. Biological control has been particularly effective in reducing cereal leaf beetle populations.

Damage caused by Hessian fly in spring wheat is becoming more frequent across parts of eastern Washington.  Crop damage from this pest may include but not limited to: stunted plants, lodging (when plants are attacked after stem-elongation), aborted tillers, and/or whole dead plants.

Grasshoppers are generalist feeders and will attack an array of plants. They may become more abundant in years when conditions are hot and dry.  A reduction in natural vegetation can oftentimes make cultivated crops more appealing, such as canola. Both nymphs and adults can cause significant feeding damage, especially when feeding occurs on the developing or ripening pods.

Mites are polyphagous, feeding on numerous different host plants such as oats, barley, spring wheat, winter wheat, corn, and other grasses such as barnyard grass. Because of their small size, mites can be spread by the wind. Fields with heavy infestations typically have a silver or gray coloration. Feeding damage causes reduced photosynthetic potential and reduced yield. The wheat curl mite is the only known vector of Wheat Streak Mosaic Virus (WSMV).

Wireworms are the immature larval stage of click beetles, and these beetles can spend several years in this larval stage feeding on germinating seeds and young seedlings, resulting in thin crop stands and lower yields.

The cabbage aphid (Brevicoryne brassicae), is a destructive species of aphid. Canola damaged by aphids in the seedling stage appears stunted and is more susceptible to winterkill. These plants will have curled leaves with shortened nodes. The canola may exhibit a purplish tint associated with plant stress. Aphid populations that develop during early bloom and pod-fill can cause deformed, stunted or completely sterile pods. Black sooty mold is also associated with aphid colonies. Aphids have also been reported to transmit several viruses to canola.

The cabbage seedpod weevil (CSPW), Ceutorhynchus obstrictus (Marsham), is an introduced insect pest from Europe and causes damage to members of the Brassicaceae or mustard family, including cultivated crops such as canola and brown mustard.

As the winter canola acreage in central and eastern Washington continues to increase, so does the threat of CSPW causing significant damage to yields if left unmanaged.

Flea beetles are usually not a problem in winter canola unless the crop is planted very early, the plants are stressed, and/or spring canola is in a nearby field and maturing. If young winter canola seedlings are the only green material for flea beetles to feed on, they can quickly move from a neighboring field with a mature crop into a winter canola field and cause damage. In spring canola, flea beetles are one of the major pests that can cause economic damage to canola in the PNW.

Diamondback moth, Plutella xylostella (Linnaeus), is not new to our area as it can be commonly found feeding on plants in the mustard family such as canola, oriental or yellow mustards along with weed species. It typically is not a pest of concern; however, in some years populations can reach large numbers and cause significant economic damage.

Grasshoppers are generalist feeders and will attack an array of plants. They may become more abundant in years when conditions are hot and dry.  A reduction in natural vegetation can oftentimes make cultivated crops more appealing, such as canola. Both nymphs and adults can cause significant feeding damage, especially when feeding occurs on the developing or ripening pods. T

The pea weevil, Bruchus pisorum (L.), is considered one of the most widely distributed species in the world and will attack both winter and spring peas. Heavy infestations of this key pest can reduce the pea seed to empty shells, severely impacting yields.