By Katie Pratt
University of Kentucky
The heat and drought conditions in Kentucky could have some insects feeding in greater-than-normal numbers on crops such as alfalfa, tobacco and some vegetables.
For alfalfa, the potato leafhopper is often a major pest during the summer. Producers may overlook this tiny insect, because the first indication that this pest is present is the appearance of wedge-shaped yellow areas on the tips of leafs.
Many caterpillars, including the green cloverworm and alfalfa caterpillar, are present in the crop to some extent every summer.
“With poor growing conditions and limited food sources, they may combine with grasshoppers to cause reduced yields and winter hardiness of alfalfa,” said Lee Townsend, extension entomologist in the University of Kentucky College of Agriculture.
Grasshoppers feed on alfalfa stems and leaves, as well as on tobacco and vegetables. Faced with a limited food supply, adults can fly a good distance to feed. Feeding usually starts along the edges of a field.
Townsend encourages producers to carefully watch the edges of fields for grasshopper activity, as extensive damage can occur quickly before a producer realizes there’s a problem.
Like grasshoppers, blister beetles will begin feeding along the edge of a field and work their way across. The beetles have long, narrow bodies around an inch long, a broad head and antennae that are about one-third the length of their bodies. Unlike most beetles, their front wings are soft and flexible. The most common species in Kentucky are all black or black with a thin, gray stripe on the wing covers.
They are active in mid-July and early August. They prefer to feed on blooming plants and gather in groups. While they do not cause significant feeding damage to the plant, they are a serious health threat to horses, sheep and cattle that consume either live or dead beetles in alfalfa pastures or hay. To avoid blister beetles, producers should cut alfalfa before blooms appear.
In addition, stink bugs are common pests of tobacco and tomatoes. They feed on the middle of the tobacco leaf, which can collapse the plant leaf tissue starting from that point and turn the leaf yellow, especially in hot weather. Because it takes a day or two for the leaf to turn yellow, the bugs will have moved on before producers can make an insecticide application.