Epicauta pennsylvanica

Black Blister Beetle
Epicauta pennsylvanica

Black Blister Beetle Epicauta pennsylvanica, close-up of head, divided thorax and antennal segment 2 short and small. August 29, 2006 Wheatley, Ontario. Ontario.
Black Blister Beetle Epicauta pennsylvanica, close-up of head, divided thorax and antennal segment 2 short and small. August 29, 2006 Wheatley, Ontario. Ontario.

Identification:
Head: Entirely dull black, covered with short dark brown hair. Faint indented mid-line down to mouth area, sometimes line is reddish-brown. Eyes barely bulging, indented (emarginate) at antenna bases.
Antenna: Black, stout; long, reaching past base of wings (elytra). Segment 1 wide; wider on the male, but longer on female. Segment 2 very short. Segment 3 as long as 1, but not wide. Rest of segments about as long as wide, only slightly tapering to tip.

Blister Beetle Epicauta pennsylvanica on Cup Plant. August 13, 2009. Wheatley, Ontario.
Blister Beetle Epicauta pennsylvanica on Cup Plant. August 13, 2009. Wheatley, Ontario.

Thorax: Dull black, covered with short dark brown hair. Base narrow, collar-like, slanting to mid thorax. Indented line down middle, slightly deeper indent (impression) at center on lower edge of thorax.
Wings (Elytra): Dull black, covered with dark-brown hair; completely covering abdomen, except for a small tip. V-shaped area at base between each wing (scutellum) small, barely visible.
Legs: Black. 2 flat, pointed spurs on hind shin (tibiae), outer one wider, longer.
Abdomen: Entirely black.

Similar Species: The only other all black blister beetle in Ontario is E. murina. It is covered with gray hair, so usually doesn’t look very black. E. murina also has antenna segments 1 and 2 very long on both male and female.

Blister Beetle Epicauta pennsylvanica on Aster. October 14, 2008 Wheatley, Ontario.
Blister Beetle Epicauta pennsylvanica on Aster. October 14, 2008 Wheatley, Ontario.

Size: 9 to 15 mm. 7.5 to 12 mm. 7 to 15 mm. Pinto 1991.

Habitat: Meadows, forest edges and crop fields.

Food: Adults feed on flowers, preferring Goldenrod and Aster, but have been found on a wide variety of others, mostly in Aster family.

Flight Time: August to October.

Blister Beetle Epicauta pennsylvanica - 2 chowing down on Cup Plant. August 13, 2009 Wheatley, Ontario.
Blister Beetle Epicauta pennsylvanica – 2 chowing down on Cup Plant. August 13, 2009 Wheatley, Ontario.

Life Cycle: Males are territorial, chasing other males away. Females form many tunnels 25 mm. straight down into the soil, and lay 15 to 150 eggs in each tunnel. Eggs are long, white, but gradually darken. Larvae hatch in about 15 days, dig out of the tunnel and search out grasshopper eggs of Spur-throated Grasshoppers Melanoplus femurrubrum, M. sanguinipes, M. spretus and M. differentialis. Larvae need to feed on over 20 eggs in a grasshopper pod to complete development. By 5th instar, it leaves pod to over-winter in the soil, pupating the next spring. One generation per year.

Comments: Essex County – Ojibway Prairies, Windsor, Ont.

For information on synonyms, references and type specimens see next page

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