Blister beetle (Epicauta pesttifera), Coleoptera

Blister beetle biology & life cycle

Also known as the caragana beetle. Adults emerge from the soil and aggregate on host plants in late spring. Adults eat foliage and can be abundant. Larvae are parasites of grasshopper egg pods and ground nesting leaf-cutter bees. Mature larvae moult to form a hard shelled overwintering stage. In spring, this larval stage moults again, pupates and emerges as an adult. One generation per year.

Identifying Blister beetle

Blister beetle: eggs

Eggs are yellow and cylindrical in shape.

Blister beetle: larvae

Mature larvae, yellow with reduced legs and mouthparts, 13mm long. Larvae of both margined and striped beetle are pale in color. First instar larvae are mobile, but later stages are very sedentary and grub-like. These larvae have 3 short pairs of ventral legs and 12 body segments.Larvae of some species will invade leafcutter nests and feed on pollen, honey stores as well as the eggs. Most larvae are beneficial because they feed on grasshopper eggs. Larvae of some species will invade leafcutter nests and fee on polle, honey stores as well as the eggs. Most larvae are beneficial because they feed on grasshopper eggs.

Blister beetle: Pupae

White.

Blister beetle: adult

10-25mm long, cylindrical body, rounded thorax. Adults move into fields in swarms, feeding on young leaves and flowers before moving to older plant parts. Adult beetles contain a toxin called cantharidin which can cause blistering on the skin. Adult blister beetles have prominent, broad heads, narrow necks, and vary from 12 to 28 mm in length. The margined blister beetle is black, gray, or a mixture of the two colors. Striped blister beetles are yellowish-orange with brown stripes.

Blister beetle: management

Monitoring for adults and their feeding damage should begin in June to early July, soon after they have emerged from the soil.