A Lacewing's Wing

georgedingwall · Post by **georgedingwall** » Tue Jan 30, 2007 7:39 am

Hi all,

Here is an image of a small area of wing from the same Lacewing that I posted a head shot of the other day.

There are two wings, one on top of the other in this image.

The field of view is about 2.5mm wide.

Does anyone know why some insects have so many hairs in places you might not expect there to be hairs. Logic would say that hairs on a wing would not be good for aerodynamics, but not many insects are aerodynamic anyway.

Do insects get some added benefit from these hairs? Maybe they give some additional lift by increasing the surface tension between the wing and the air. A bit like a feather falling more slowly than a brick. If that was true, it would mean the insect had to expend less energy to stay in the air than if they had no hairs.

Bye for now.

Moebius · Post by **Moebius** » Tue Jan 30, 2007 8:38 am

George,

It may not be the primary function, but I did find the following abstract by W. Mitchell Masters and Thomas Eisner that discusses one beneficial purpose to those wing hairs:

Abstract: "When green lacewings (Neuroptera: Chrysopidae) fly into spider orb webs, they often simply reverse their flight direction and pull away (Table I). If a lacewing is trapped, it uses a specialized escape behavior. It first cuts away the sticky strands entangling head, feet, and antennae. If an antenna cannot be freed by tugging, it uses an antenna climb (Fig. 5A). After its body is free, the lacewing remains suspended by its hair-covered wings, which are held in a characteristic cruciform position (Fig. 5B). Orb web sticky strands adhere poorly to the hairy wings (Fig. 7), so the chrysopid may just wait until the strands slide off and it falls free. If placed in an orb web when the spider is at the web hub and ready to attack, a lacewing usually does not have time to escape (Fig. 1). When the spider is at the hub but eating, the chances of escape improve, and when the spider is away from the hub attacking other prey, nearly all lacewings in our experiment were able to escape. This finding emphasizes the importance of the spider's activity in its capture success."

Ken

georgedingwall · Post by **georgedingwall** » Tue Jan 30, 2007 9:14 am

Hi ken,

Your information sounds plausible.

I never really thought of something as delicate in appearance as a Lacewing having a strategy for getting out of spider webs. I assumed that the large wing area, relative to body mass, would have meant it would be permanently trapped.

I wonder how W. Mitchell Masters and Thomas Eisner got the job of experimenting on Lacewings trapped in spider webs. Sounds like the sort of thing I wouldn't mind having a go at.

Bye for now.

beetleman · Post by **beetleman** » Tue Jan 30, 2007 11:21 am

Well, how about This....maybe the hairs act like the dimples on a golf ball. They help reduce the drag on the surface of the wing by breaking up the air currents. I cannot quote the physics of it. If you think about it, a lot of Beetles and insects have lots of dimples in their wing covers.

. If the hairs are connected to nerves, I would have to guess they supply the insect with some kind of information. Cut the hairs off and see if it effects the flight!!

DaveW · Post by **DaveW** » Tue Jan 30, 2007 11:58 am

I put "Purpose of hairs on insect wings" into Google but did not really turn up anything. However I stumbled on this site you yanks might find interesting:-

http://www.cirrusimage.com/

DaveW

beetleman · Post by **beetleman** » Tue Jan 30, 2007 12:09 pm

Thanks Dave...another great link

That Brown Recluse Spider - Loxosceles reclusa is a pretty creepy article