Bumble Bee Mimic

One of the most enjoyable natural history monographs that I've come across is The Systematics of Lasiopogon (Diptera: Asilidae) by Robert A. Cannings, curator of entomology at the Royal British Columbia Museum in Victoria, Canada (2002). While I've yet to encounter a robber fly from this genus, I learned a lot from this book, especially from the section about the biogeography of Lasiopogon, which has implications or parallels to other insects that share Holarctic distributions. Here's Cannings' description of the family Asilidae:

"The robber fly family (Diptera: Asilidae) contains more than 6,700 described species worldwide. Robber flies are predators that as adults pursue other insects (usually flying ones), seize them and kill them with paralysing saliva injected through the hypopharynx (tongue). They then suck up the liquefied contents of the prey through the proboscis. The morphology of the adult fly, especially the prominent eyes, the mouthparts and the raptorial legs, reflects this mode of prey capture and feeding. Robber flies usually hunt in open, well-lit areas and are most active in the warmest part of the day; overcast skies greatly curtail their activity. Different genera, and often different species within a genus, have different hunting behaviour and preferences for perching sites."

For our area, Minnesota and Wisconsin, the most useful resource has to be the Robber Fly guide included on the Wisconsin Butterfly website (www.wisconsinbutterflies.org). The genus Laphria includes a number of very convincing bumble bee mimics, including the impressive Laphria thoracica, which I had the pleasure to observe today in our backyard. The give away is the way they perch on leaves; bumble bees just don't stand on leaves like this. Of course another tell is seeing them fly out and then return to their perch with their prey stabbed to their face.

Posted on 14 de junho de 2017, 03:58 AM by scottking