Blister Beetles
From Bugwoodwiki
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Author: Dr. Phillip Roberts, Dr. Paul Guillebeau, University of Georgia
Contents |
Description
Adult blister beetles have broad heads, narrow necks, and vary from 12 to 20 mm in length. Several species are recognized. Two of the most common include the margined and striped blister beetles. The margined blister beetle is black, gray, or a mixture of the two colors. Striped blister beetles are yellowish-orange with brown stripes. Larvae are pale in color. First instar larvae are very mobile, but later stages are sedentary and grub-like.
Hosts
Blister beetles have a wide host range including alfalfa, clover, soybean, potato, tomato, melon, cotton, and eggplant.
Damage
Blister beetle larvae are considered beneficial since they destroy grasshopper eggs. The adults are potentially damaging foliage-feeders. Often blister beetle infestations are localized in small areas (< 1/2 acre). Severe defoliation may occur in these areas. On soybean most damage occurs as a result of foliage feeding, but some pod and flower feeding may occur.
Life Cycle
Blister beetles overwinter as late instar larvae 1 to 2 inches deep in the soil. Overwintered larvae pupate in the spring, and adults emerge in late May and June. During summer they congregate and feed on foliage and flowers (depending on species). Masses of 50 to 300 yellow cylindrical eggs are laid in the soil. Eggs hatch in 1 1/2 to 3 weeks, and young larvae search for grasshopper egg cases. A few days after finding and feeding on the egg case, the larva molts and becomes fairly inactive but continues to develop and feed on the grasshopper eggs. Fat, almost legless fifth instar larvae create an earthen chamber in which to overwinter. Development usually continues the next spring but larvae may remain inactive for two years.
Control
On soybean control is rarely necessary due to localized infestation. Spot treatment may be an alternative. Treat based on defoliation thresholds.
