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Robber Fly - Laphria thoracica
Family Asilidae
Species Laphria thoracica Fabricius, 1805 / Synonyms: Laphria
alcanor Walker, 1849 / Laphria fulvithorax Fabricius, 1805
Live adult female fly photographed at West Chicago Prairie,
DuPage County Illinois June 20, 2005. Size: 26mm
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These fearsome
predatory flies use the energy-efficient
"wait and pounce" hunting stratagem. I
find this habit defeats the otherwise
superb bumblebee mimicry; these flies
sit stationary while bumblebees almost
never do unless they are sick or dying. |
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| Flies in the Diptera family Asilidae are commonly known
as robber flies. The family Asilidae contains about 7,100
described species worldwide. 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 through the proboscis. Many species
have long, tapering abdomens, sometimes with a sword-like
ovipositor. Others are fat-bodied bumble bee mimics. Adult
robber flies attack other flies, beetles, butterflies and
moths, various bees, dragon and damselflies, ichneumon
wasps, grasshoppers, and some spiders. -- From Wikipedia |
Huge compound eyes give the robber fly excellent vision for mid-air
intercepts.
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HULL (1962): "The ROBBER FLIES, or ASILIDAE,
comprise one of the largest and most abundant families of
present day insects. Distributed through all parts of the world,
over 400 genera [now
530] and subgenera have been proposed and about 4,761
species are known [now
7,003]. In addition, 18 genera and 39 species have been
described from Eocene, Oligocene, and Miocene; 15 of these
genera are also Recent [cf.
Fossil]. Because of their predatory habit of feeding on
other insects and their voravious appetites, they contribute to
the maintenance of the natural balance among insect populations.
To some extent, parasitic wasps and flies are taken by them, but
much of their prey consists of plant-feeding insects. Certain
species are known to seriously deplete the populations of
apiaries. The adults are, with few exceptions, active flies, of
considerable size and readily attract attention.
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From Asilidae
website of Fritz Geller-Grimm |
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This spectacular bumblebee mimic measures 26mm (over 1 inch)
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