Tuesday, July 11, 2017

Bee Flies

Bee fly
I saw this little fly flitting around me on the deck on Saturday.  It wouldn't hold still for a picture but I was able to get it in a bug box and chill it for its blog debut.  I sent it in to Bugguide and within 24 hours had an ID of Hemipenthes spBeyond their information, I couldn't find any other details on the genus.

According to the Hemipenthes genus page, its name means "half veiled in black", a good description of the wing pattern.  They range from 6 to 12 mm (mine was 9mm) and have short metallic hairs on the thorax and/or abdomen.  Like other members of the bee fly (Bombyliidae) family, they are ectoparasitoids, laying their eggs near the eggs or larvae of solitary bees, beetles, wasps and other insects.  The bee fly larva lives off the victim, eventually killing it.

Halteres - REK
Bee flies are in the Diptera or true fly order, the common names always separate (think "house fly").  When you see the name one word (think "dragonfly") they belong to another order.  Diptera means "two wings", separating it from the other orders that have two pair of wings.  The posterior set of wings are modified to clubbed sticks called halteres, extending from the thorax.  These vibrate with the wing beats, sending messages to the fly about its position and balance, acting like a gyroscope.  That is one reason they are so hard to swat!
Belly up

Just when I thought I was through, our friend Debbie sent me this photograph to ID.  I used my years of training and experience to identify it within a minute.  (My secret:  Google "black bee fly", look at "images" and it was the 5th on the page.)  This is a Tiger bee fly, Xenox tigrinus.   Like other members of the family, it doesn't sting or bite.  We don't even know what the adult eats!  The good news for homeowners is that it specializes in parasitizing carpenter bees.

Carpenter bees drill smooth holes in wood to lay their eggs in, and have been working on our cabin beam.  Fortunately they don't cause significant structural damage and they are good pollinators.  Still, if the Tiger bee fly wants to feed its young, I will send it our address.

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