About the time local berries reach maturity and are ready to be picked, fruit-eating insects show up to reap the fruit of growers’ labors. Common fruit-eating insects in Utah include the stink bug, lygus bug, earwig, grasshopper and several species of fruit-eating wasps.
According to Diane Alston, Utah State University Extension entomologist, damage occurs when the insects suck or chew the individual drupelets and sometimes even remove the entire fruits.
“To help prevent economic yield loss, growers and home gardeners should inspect ripening fruits several times a week,” she said. “They can place a cloth or plastic tray under the plants, then shake the canes to dislodge insects. If damaging insects are found, they can be removed by hand or sprayed with an insecticide. If insecticides are used, it is important to read the product label to determine the pre-harvest interval or required waiting time between application and picking fruits. There are also plant cultural practices that can reduce the abundance of fruit-eating insects.”
Recommended insecticides with low toxicity to humans are neem oil (Azatin) and spinosad (Success, Entrust). Conventional insecticides that deter fruit feeders include carbaryl (Sevin), malathion, permethrin and esfenvalerate.
Utah residents who need help identifying berry-eating insects or information on pest management can contact Utah State University Extension and the Utah Plant Pest Diagnostic Lab, Alston said. It is important to accurately identify insect pests in order to manage them.
The Consperse and green stink bugs are one-half to five-eighths inches long with a shield-shape, flattened body. The Consperse stink bug is speckled brown with pointy “shoulders” and the green stink bug is a bright green color. Both stink bugs feed on individual drupelets and cause them to shrivel. They release an offensive odor and contaminate the berries at harvest.
Lygus bugs are one-fourth inch long, green and brown in color and are attracted to flowers and developing fruit. They cause misshapen fruit by feeding on individual drupelets. They are usually present at low density and do not cause economic damage to raspberries.
European earwigs are one-half to three-fourths inch long, shiny brown and have a pair of claspers at the tip of the abdomen. They are nocturnal and their presence or damage may go unnoticed until harvest. Earwigs feed on fruit and foliage. To manage them, remove weeds from around the base of canes and vines. Keep rows clear of debris. Earwigs can be trapped by using Tanglefoot® or a similar adhesive at the base of canes to prevent them from crawling into plants. To monitor for them, place boards or rolled-up newspapers next to berries in spring and check weekly for hiding earwigs. Treat the ground and lower canes with carbaryl at the beginning of spring activity when earwigs are found.
In areas where berry fields are located near open rangeland or undeveloped land, grasshoppers may move onto canes at harvest time to feed on fruits and leaves. Fruit-protecting insecticide treatments may be effective. Insecticide bait (bran coated with carbaryl or Nosema locustae, a protozoan biological control) placed around field borders when young grasshopper nymphs are first seen may reduce populations. Repeated bait applications will likely be necessary, but it is important to note that insecticide baits are not effective at killing adult grasshoppers.
The yellow jacket and European paper wasp are common berry eaters that also sting those who disturb them. Yellow jackets nest in the ground, and nests can be treated with conventional insecticides, dug up, removed and destroyed. Placing commercial traps that contain heptyl butyrate bait at the perimeter of berry fields can also reduce yellow jacket numbers. The European paper wasp builds umbrella-shaped nests under the eaves of buildings and other protected sites. Paper wasps are not attracted to yellow jacket traps. Removing nests and protecting fruit with insecticides near harvest may provide control.
USU Extension has offices throughout the state, and local Extension agents can assist with pest identification and insecticide use. The Utah Plant Pest Diagnostic Lab, located on the USU campus in Logan, provides pest diagnostic services and pest management education for commercial growers and homeowners. Sample submission information is available at http://utahpests.usu.edu/uppdl and information on other Utah pests can be found on the USU Extension Utah Pests homepage at http://utahpests.usu.edu.
By: Julene Reese - Jul. 9, 2007