Margined Blister Beetle
Head: Almost entirely black, or covered with varying degrees of gray pile, but always a black spot on top of head. Faint indented line down middle of head. Eyes slightly bulging, indented (emarginate) around antenna bases. Long black whiskers (palpi); males have longer, flatter segments than female; last segment longer than eye width on both male and female.
Antenna: Black, thin. Segment 1 only slightly wider than others. Segment 2 shortest; 3 longest. Rest of segments 2.5 times as long as wide (Main ID). Although segments become progressively thinner, they retain the same length on each segment to tip. Antenna are more slender and longer than in Epicauta cinerea.
Thorax: Black, narrower than head; neck or base area very narrow, sides slanting out to middle of segment. Varying amounts of gray pile along side edges and down the middle. Note: narrow
base may not be visible depending on tilt of head.
Wings (Elytra): Black, outlined along side edges and down middle with gray pile. Tips of wings slightly narrowed at center divide. Tip of abdomen usually visible, more so on female.
Legs: Black, covered with varying amounts of gray pile. Spurs thicker than in Epicauta cinerea. No white patch on underside of thigh (femur) like E. cinerea.
Abdomen: Gray with black stripe between segments. Tip black. Abdomen thicker on female.
Note: Two other colour forms: entirely black to brownish-black in south-west U.S. and entirely gray (cinerous) to light brown in southern mid U.S. Neither form is present in Ontario.
Similar Species: Length of each segment of antenna on Epicauta cinerea become progressive shorter to tip, and segments are wider. On Epicauta funebris segment length remains constant; segments much thinner. Antenna barely reach to base of wings (elytra) on E. cinerea. On E. funebris they extend past base of elytra. E. cinerea spurs are narrow, hair-like; whiskers (palpi) segments are shorter and both antenna and whiskers are hairy.
Size: 8 to 21 mm long. Average 12 to 16
Habitat: Forest edges, meadows, field crops.
Food: Listed as a pest of alfalfa, potatoes and soybeans, but feed on a wide variety of plants, preferring the flowers: Nightshade family Solanaceae like Clammy Weed Physalis heterophylla, beets, eggplant, tomato, Ragweed Amaranthus, Devil’s Walking Stick Aralia spinosa, Morning Glory Ipomoea, wild grapes Vitis.
In Wheatley they are especially fond of Cup Plant Silphium perfoliatum both flowers and leaves, Black-eyed Susan flowers and even Lilypads Nymphaea, and farmer’s field crops of potato, soybean and tomato.
Flight Time: Mid July to early September.
Life Cycle: Females dig tube-like tunnels in an inch of soil and lay an average of 300 yellow eggs in a masses of about 30 each and cover them up. Eggs hatch 3 to 4 weeks later and larvae search out grasshopper eggs in the soil; the Two-Striped Grasshopper Melanoplus bivittatus and the Differential M. differentialis. Although late in the season, larvae reach the 6th instar before winter and continue feeding all winter. Some pupate the next spring and some can wait for another year.
Larvae accumulate cantharidin, a defensive chemical, during all stages of development. Adult females lose the chemical as they mature, but males have an increase of cantharidin which is transferred to the female when mating. The chemical is also discharged from the leg joints as protection from predators.
Comments: Not listed for Ontario. BugGuide has a series of 4 photos from Mississauga, Ontario (found on wild grape) listed under the generic section Cinerea Group.
Recorded from Wheatley, Ontario since 2006.
For information on synonyms, references and type specimens see next page