Friday, August 20, 2010

Robber Fly

Robber Fly with Kill

There’s a thief among us--
a predator who snatches one, then another, from her lookout on the rusty rail of the field fencing in my overgrown pasture.


She takes to the air and effortlessly grabs hapless insects in mid-flight, wrapping her spiny legs and clawed feet around some larger than herself, while some are smaller and easier prey.

Robber Fly with small wasp or ant

With little chance of escape, they’re instantly immobilized by a dose of neurotoxic and proteolytic enzymes deftly delivered through the tip her dagger-like proboscis.
Within minutes, she’s drinking them down.
Robbed of the life within, an empty shell falls to the ground.

Robber Fly preying upon Common Whitetail Dragonfly

Robber flies are skilled predators of the insect world and, though usually of no harm to humans, able to inflict a painful stab if handled carelessly. Many genera and species exist worldwide, some fairly small and some rivaling bumblebees and dragonflies in size.
This particular individual may be of the genus Promachus or Proctacanthus, both large and aggressive, bearded robbers.



There are many dragonflies left in my field.


Common Whitetail dragonflies
2 males (above) and female (below)

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10 comments:

Weeping Sore said...

Eeeuuww on the fly. I do love the dragonflies. Here in So Cal we have orange and red ones and once in a while blue ones. Yours are gorgeous

KaHolly said...

Nina, great photos to accompany your delightful text today. I love learning new things. Thank you. ~karen

Cape May Wren said...

Serendipitously stopped in to add your blog to my "following" list and was gifted with an ID--it seems I was peering at a robber fly myself just yesterday...

Also would like to say your photos have been especially luminous lately. Thank you for taking the time to share them!

nina at Nature Remains. said...

Cape May Wren--I've noticed the very same thing...I'll come across something in my field and lo and behold--we've all stumbled across it, similar stories pop up everywhere.
Glad you've discovered the missing ID--there's a wide range of robber flies out there. Check out this link for more IDs:
http://www.pbase.com/tmurray74/robber_flies

Karen--thanks for taking me to Maine!

Weeping Sore--I love the dragonflies, too. And this time of year, they're ALL over!

sciencedude288 said...

Proteolytic and neurotoxic venoms! Not a fun way to go.

nina at Nature Remains. said...

No kidding!
They take effect so quickly that even if the fly were to drop its prey, it would have been dealt the fatal blow.
The insect world is the stuff nightmares are made of!

Jim McCormac said...

Very cool - robber flies are some of the most interesting insects out there! The big one with bands on the abdomen looks to be the amazing Red-footed Cannibal Fly, Promchus hinei. These are real barbarians, capable of taking down prey much bigger than they. I have seen tem take down large fuzzy bumblebees, and have heard of them taking out hummingbirds.

Jim

Nina said...

Thanks, Jim--
I had a feeling it might be the Red-footed Cannibal Fly, but I started looking at all the possibilities and how closely you had to examine them in order to be sure and felt I might be jumping in over my head. She certainly had a death grip on the dragonfly--and was quite the predator.
I seem to be seeing a lot of these around lately--I don't know if there are really a large number at this season, or if I just seem to be more focused on seeing them!
Pretty cool, to be sure.

gecko said...

I have seen the robber fly in our garden in New Zealand, but never knew what it was called. Great pics!

Tuga7 said...

beautiful details, like the focus and sharp obtained.