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Robber Fly - Holcocephala calva and H.
abdominalis |
 I think this is Holcocephala calva |
| There are over 7,000 species of
robber flies world wide; nearly 1,000 in North America. All robber
flies have stout, spiny legs, a dense moustache of bristles on the face
(mystax), and 3 simple eyes (ocelli) in a characteristic depression
between their two large compound eyes. The mystax helps protect the head
and face when the fly encounters prey bent on defense. The antennae are
short, 3-segmented, sometimes with a bristle-like structure called an
arista.
The short, strong proboscis is used to stab and inject victims with saliva containing neurotoxic and proteolytic enzymes which paralyze and digest the insides; the fly then sucks the liquefied meal much like we vacuum up an ice cream soda through a straw. Many species have long, tapering abdomens, sometimes with a sword-like ovipositor. Others are fat-bodied bumble bee mimics; the effect is quite convincing. Take a close look at any insect that looks like a bumble bee if it's sitting on a leaf - chances are, it's a robber fly. (Bumble bees as a rule do not sit in one spot for more than a few seconds). |
These two specimens are H. abdominalis
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