Arthromacra aenea

Darkling Beetle
Arthromacra aenea

Darkling Beetle Arthromacra aenea on Poison Ivy leaf. Jun 18, 2009. Wheatley, Ontario.
Darkling Beetle Arthromacra aenea on Poison Ivy leaf. Jun 18, 2009. Wheatley, Ontario.

Identification: Entirely dark bronze with slight greenish tint in Ontario – other colours elsewhere.

Head: Eyes small, notched. Whiskers (palpi) slightly lighter bronze.
Antenna: Long, reaching to wings. Light yellowish-bronze to reddish-brown. 1st and last segments darker. Last segment very long: on female as long as the 2 previous segments; on male as long the 3 previous segments.

Darkling Beetle Arthromacra aenea on Grape leaf. Jun 19, 2008. Wheatley, Ontario.
Darkling Beetle Arthromacra aenea on Grape leaf. Jun 19, 2008. Wheatley, Ontario.

Thorax (Pronotum): Cylindrical, base narrower. No neck.
Wings (Elytra): Wider than thorax, coarsely punctured, but no ridges or grooves. Tips bluntly angled.
Legs: Dark bronze, feet (tarsi) usually reddish-yellow mixed with brown, but can be darker.

 

 

Similar Species: Statira species have a neck and wings are ridged, otherwise identical, including long last antenna segment.

Darkling Beetle Arthromacra aenea on Grape leaf. Jun 26, 2008. Wheatley, Ontario.
Darkling Beetle Arthromacra aenea on Grape leaf. Jun 26, 2008. Wheatley, Ontario.

Size: 9 to 14 mm.

Habitat: Found on vegetation, mostly grape leaves.

Food: Unknown

Flight Time: June to August

Life Cycle: Larvae perhaps live in rotten wood or in leaf litter. Life cycle unknown. Adults attracted to lights at night.

Comments: Essex County per photos. Listed for Ontario from Bruce Peninsula, London, Toronto area and north.

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

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