Claws of a cutworm

rjlittlefield · Post by **rjlittlefield** » Sun Oct 22, 2006 12:16 am

This is a twig's-eye view of one proleg of a cutworm caterpillar. Prolegs are the fleshy pseudo-legs along the abdomen. They come equipped with a lot of little hooks, called "crochets", shown here in the fully extended grasping position.

Canon 300D, 10X NA 0.25 objective, stacked at 0.00033 inch, severe crop resized to 2/3 of actual pixels.

Perhaps you've wondered how come caterpillars are so "sticky" when they get on your clothes. These hooks are the reason!

Well, they're the mechanism, anyway. The stickiness is triggered by the perversity of the caterpillar. It can extend or completely withdraw the crochets at will. If the caterpillar wanted to let loose, it could do that with no problem at all. It just doesn't want to.

I had not noticed the bristle under the prolog before I took this stack. But it strikes me as being in a very handy place to feel when the prolog is close enough to grab something. I don't know for sure -- it's just an idea.

I was also surprised to see the numerous broken crochets. It's odd to see anything so obviously broken at this size. But I don't think it happened during specimen prep. Maybe this caterpillar just had some tough experiences since its last molt.

--Rik

Cyclops · Post by **Cyclops** » Sun Oct 22, 2006 1:43 am

Nest shot! So its a combination of cats claws and natural velcro, cool shot!

Ken Ramos · Post by **Ken Ramos** » Sun Oct 22, 2006 3:35 am

Noticed those broken hooks right off Rik, could be like sharks teeth, maybe it has a few more in reserve. The little guy sure has dirty feet but I guess if I were a cat...

Anyway a great shot, lots of detail in the tootsies, it's nice to know how somethings work.

beetleman · Post by **beetleman** » Sun Oct 22, 2006 5:31 am

Very interesting and different...thats what I like about it. Great detail on that anatomical insect part Rik.

I would assume that the hooks might get wedged into small cracks in something and not come out that easily and with the great number of them, a certain percentage can be broken until the next molt.

MacroLuv · Post by **MacroLuv** » Sun Oct 22, 2006 9:23 am

Getting shudder just thinking about claws and hooks.

rjlittlefield · Post by **rjlittlefield** » Sun Oct 22, 2006 7:47 pm

Ken, if you think this is dirty, you should have seen the beast before I cleaned it! (Water jet from a small syringe -- these guys are waterproof.)

Doug, I like that "get wedged" theory. The caterpillar really is very strong compared to a single hook. Maybe it just breaks one off periodically. I'll have to check this out, next time the caterpillars are common.

--Rik