Vegetable Crop Insects – July 17, 2015

Joanne Whalen, Extension IPM Specialist;

Lima Beans
Continue to sample for mites since early detection is necessary to achieve effective control. We are starting to see an increase in stinkbug and plant bug populations. As soon as pin pods are present, be sure to watch carefully for plant bug and stinkbug adults and nymphs. As a general guideline, treatment should be considered if you find 15 adults and/or nymphs per 50 sweeps. In the earliest planted fields, you should also start watching for corn earworm.

Continue to scout all melons for aphids, cucumber beetles, and spider mites. Although aphid populations still remain low in most fields, we continue to see localized infestations. Early detection is critical since populations can quickly explode. You should also continue to watch for beet armyworm, yellow striped armyworm, and cabbage looper larvae feeding on the rinds of watermelons. If beet armyworm (BAW) is in the mix, it is important to select a material that is effective on this insect pest. Please refer to the Commercial Vegetable Recommendations for materials labeled for BAW control in melons.

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 (BAW) larvae since they can quickly defoliate plants. In addition, be sure to use a material that provides beet armyworm control – the pyrethroids will not control this insect. Please refer to the Commercial Vegetable Recommendations for materials labeled for BAW control in peppers.

Snap Beans
In processing snap beans, you will need to consider treatments for both corn borer and corn earworm. Sprays are 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
Continue to sample all fields through pre-tassel stage for whorl feeders (corn borer, corn earworm and fall armyworm). A treatment should be applied if 12-15% of the plants are infested with larvae (regardless of the species). The predominant whorl feeder being found at this time is the fall armyworm. Since fall armyworm (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 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 We are also hearing reports of aphids being found in sweet corn. Sprays for aphids need to be applied before populations explode. Be sure to refer to the Commercial Vegetable Recommendations for materials labeled on sweet corn for aphid control.