Tuesday, July 12, 2011

Crane Flies -- Tipulidae

“What’s this?” asked one of the young men at the Brooks Bird Club Foray, as he held this in front ofm y face. “Well, it’s a  a  uh”, then my friend piped up with “Crane Fly Larvae”.  I just looked at her in awe when I realized that this large fat creature, almost the size of my little finger, turned into a delicate long legged crane fly.  This one was found in the stream that was nearby. The larvae live in a variety of moist habitats such as fast moving steams, marshes, tree holes, decaying plant debris and decomposed wood. They feed on decaying plant material and some smaller insects. Most are beneficial decomposers.
The larvae have thin, tough skins and a head (left) than can be withdrawn into the thorax. The shape, length and lobes found at the posterior end can often be used to identify species. Had I know that at the time I would have taken a photo but I think you can see the lobes on the end at the right.
I am far more familiar with the adult crane fly, a member of the Tipulidae family, having just rescued my friend from the sight of one in my house just last week. They look like giant mosquitoes but they are vary harmless and do not bite at all. The can be just over 2 inches but when they fly slowly by with its long legs dangling it seems like it is out to get you.  Like all true flies (Diptera order), carne flies have only two wings.

The males have blunt abdomens and have an erratic flight pattern of ups and down and rotations. See below.

The females fly in a more direct route and have pointy abdomens used to lay their eggs. See below.

The life cycle is one of complete metamophosis with eggs, larval, pupal and adult stages.  The adults live about 15 days, just enough time to mate and lay eggs.

I have not read about eye shine in crane flies but it looks like they are different in my photos. One is green and the other blue.  These photos were taken at my porch light while I was photographing moths. As you can tell I was not focusing on identification characteristics so I’m not sure what species these are. Lesson learned: always take the time to get those identifying marks because you just never know when you will want them.

I have barely touched the surface on what is known crane flies and I hope your curiosity is piqued to learn more.

My first close up experience with adult crane flies was at the Leadership Training Camp in Terra Alta, WV. Chen Young, an international expert was a member of the teaching team and he showed me how to preserve them without breaking the fragile legs. He has a wonderful web site, and I recommend that you give it a look. There are more than 1,500 species in North America and over 300 are known from Pennsylvania. This is probably because Dr. Young lives and does most of his collecting in that state.  Crane fly study is an area where still little is known and there is room for amateurs to make a lot of contributions.

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