Vegetable Crop Insects – July 29, 2016

Joanne Whalen, Extension IPM Specialist;

Lima Beans
You should continue to sample for mites, plant bugs and stinkbugs. It is also time to begin checking the earliest planted fields for corn earworm. A treatment will be needed for corn earworm if you find one corn earworm larvae per 6 foot-of-row.

You should continue to scout all melons for aphids, cucumber beetles, and spider mites. We are starting to see an increase in cucumber beetle adults that can feed on the rinds of melons. It is also the time of year to start watching for caterpillars, including beet armyworm, yellow striped armyworm and cabbage loopers, which can also feed on rinds. It will be important to determine if beetles and/or caterpillars are doing the damage since chemical selection will be different. Be sure to read all labels carefully for pollinator protection statements, rates and restrictions. Some materials are restricted to only one application as well as ground application only.

Depending on local corn borer trap catches, sprays should be applied on a 7 to 10-day schedule once pepper fruit is ¼ – ½ inch in diameter. Be sure to check local moth catches in your area by calling the Crop Pest Hotline (302-831-8851) or visit our website at At this time, you will also need to consider a treatment for pepper maggot. Be sure to also watch carefully for beet armyworm larvae since they can quickly defoliate plants. In addition, be sure to use a material that provides beet armyworm control – the pyrethroids have not provided control of this insect in past years.

Snap Beans
Depending on local trap catches, sprays may be needed at the bud and pin stages on processing beans for corn borer control. As earworm trap catches increase, an earworm spray may also be needed at the pin stage. You will need to check our website for the most recent trap catches to help decide on the spray interval between the pin stage and harvest for processing snap beans. Once pin pods are present on fresh market snap beans, a 7 to 10-day schedule should be maintained for corn borer and corn earworm control.

Sweet Corn
At this time, the main whorl feeder being found is the fall armyworm (FAW). A treatment should be applied if 12-15% of the plants are infested with larvae. Since FAW feed deep in the whorls, sprays should be directed into the whorls and multiple applications are often needed to achieve control. FAW can also be a problem in silk stage sweet corn, especially in outbreak years. The first silk sprays will be needed for “worm” control as soon as ear shanks are visible. Be sure to check both blacklight and pheromone trap catches since the spray schedules can quickly change. Trap catches are generally updated on Tuesday and Friday mornings on our website ( and the Crop Pest Hotline (302-831-8851). Information on scouting sweet corn and how to use the trap catch information can be found at