Wedge-Shaped Beetle - Macrosiagon sayi

Moved

… Ron M., 13 February, 2009 - 10:32am

Macrosiagon species, distinctive elytral markings

This appears to be Macrosiagon based on illustrations and key in Arnett, How to Know the Beetles. (1) See Identification section of guide page for details.

This species has those distinctive creamy bands on the elytra and is not the same as other photos of yours, which appear to be M. octomaculatus, nor the same species I've seen in North Carolina, nor what is apparently M. limbatus seen by Beatriz in Pennsylvania. This Florida checklist might narrow the possibilities.

Patrick Coin
Durham, North Carolina

… Cotinis, 5 January, 2005 - 6:17am

Macrosiagon sayi Rivnay 1929, female

Patrick-

It's kind of hard to tell from the photo, but the general coloration (never a sure thing in Macrosiagon), the locality, the shape of the vertex of the head, and the first tarsal segment appearing distally flared make me think this is a female specimen of M. sayi. This is a relatively rare species and poorly characterized- a good find!

cheers,

zack

… Zack Falin, 8 March, 2005 - 8:24am

Ripiphoridae wedge-shaped beetle

This is a female wedge-shaped beetle in the family Ripiphoridae, probably genus Macrosiagon. They are really weird parasites of solitary bees. Females lay eggs on flowers. The eggs hatch into tiny, active larvae called triungulins that grab onto a visiting female bee. When she arrives back at her nest burrow, her hitchhiker disembarks ("de-bees?"), and goes in search of the bee's offspring. From there, several things can happen, but eventually the triungulin metamorphoses into a "couch potato" while feeding on the pre-pupal bee. Told ya it was strange:-) Nice find.

… Eric R. Eaton, 5 July, 2004 - 3:33pm

Thanks!

Eric & Patrick,

Thanks for the info on this (and the other) beetle. It always amazes me to discover the life cycle of an insect that you see briefly enough to observe and photograph. Very cool!

… Tony DiTerlizzi, 6 July, 2004 - 6:43pm

added guide

Great photo and fantastic life history information. I added a guide for this family to save Troy the trouble.
I'll have to look for these now--I am glad wiser ones than I have shown me what these oddities look like.

Patrick Coin
Durham, North Carolina

… Cotinis, 5 July, 2004 - 6:35pm

Moved to guide

Thanks as always, Patrick. I'm itching to create a move feature to ease this sort of thing.

… Troy Bartlett, 6 July, 2004 - 9:48pm