What's that bug?

[Wild One]

Recently I stopped in to observe a small, local pond. It was a sunny day, temps around 40-45ish and the pond has been ice-free for a couple weeks now. I observed several light-olive/cream-colored nymphs swimming toward the surface of the water, or just swimming along with the wind-blown current. This was awesome for me as I had never, in all my years of fishing, actually seen any aquatic insects swimming. I had a new found appreciation for some of our more popular nymph patterns and some enlightenment on how I could improve my patterns.

I went back two days later on a colder, cloudier day hoping to locate some of the rainbows that were stocked in this typical warm-water pond. I wasn't able to observe any of these nymphs; however, I saw a great number of shucks floating in the surface film and a good number of diptera (two-wing flies) flying a floating along as well. They were similar in color to the nymphs I observed a few days before, maybe a little darker olive. I readily recognized these flies as I have seen millions of them around just about every warm water lake or pond I've ever been to. They do not bite and would be equal in size to about a size 14 dry fly hook.

I am wondering if anyone out there knows a little about these flies. I've never seen them in or around any cold body of water (eventhough the water temp of this pond had to be less than 50). What are these flies? Do fish feed on them? What patterns are regularly used to imitate them? My first thought when I saw the nymphs was mayflies. This would hold true back home (March is famous for the first BWO hatches) but I don't know much about the midwest yet. Also, when I saw the adults flying around I knew they weren't mayflies. The adults hold their wings down against their backs almost like a caddis at rest, but they're flat and not tent-shaped.

I recently read a great article about chironomids and wonder if these are chironomids. I'm not familiar at all with chironomids. Is anyone out there familiar with these little flies/nymphs?

[Bluegill222]

any chance of a picture? Something to suggest the general shape of the nymphs and/or adults?

[JohnScott]

See reply on the Fly Anglers Online forum.

[Taxon]

Wild One-

I recently read a great article about chironomids and wonder if these are chironomids. I'm not familiar at all with chironomids. Is anyone out there familiar with these little flies/nymphs?

Yes, from your description of those which had emerged and were flying around, they would likely be Chironomids. Hope this is not being unnecessarily technical, but the immature lifestages of true flies (Dipterans) are larva and pupa, rather than nymph. The primary reason I mention this is that the Chironomid pupa is the probably the most successful lifestage to imitate. It looks like this:

[rnelson]

I agree with Roger that your description strongly suggests chironomids. This group of aquatic insects is widely distributed and occurs in a huge number of habitats. My Ph.D research was on chironomids and I can tell you that they are a challenging group taxonomically. In many aquatic habitats make up an incredible amount of the invertebrate biomass. I tie several different versions of the larvae and pupae.

Roger has a great web site on aquatic entomology. Check it out for lots of really good information.

Rick

[Wild One]

Guys,
Thanks for the responses. Roger, that picture looks exactly like the shucks I saw all over the surface film.

Do these larvae swim? If/when they swim do they wiggle? what I mean by wiggle is do they swing the back half of their bodies from side to side while swimming? Also, most everthing I've read suggests chironomids emerge to the surface very slowly. These things were swimming/wiggling like crazy.

[thezugbug]

Not sure exactly where you live, but if I heard that description here in the NE in the spring, I'd say it was a damsel nymph. Midges don't really swim from what I've seen, they sort of wiggle/struggle. Most people are really surprised when they first see a damsel swimming, it's an almost snake-like motion. Very controlled.

[Taxon]

Wild One-

Chironomid larvae generally rely on full-body undulation for locomotion, at least when unable to crawl. Pupae also employ this full-body undulation for locomotion, but mostly rely on trapped gasses to aid their slow rise to the surface.

[Wild One]

Woops. I mispoke. I meant to ask about the pupae, not the larvae. This is what the adults looked like: http://cache.eb.com/eb/image?id=9988&rendTypeId=4

Like I said earlier, the shucks in the water looked like the picture posted earlier, but I could have sworn that the pupae had legs. Looks like I may have seen nymphs that aren't connected to the midges and shucks I saw the second day. I'll keep searching for a picture of something that looks like the nymphs I saw.

[rnelson]

Wild One,

Google Chironomidae and you will find plenty of pictures of larvae, pupae and adults. One of the best sites is The Chironomid Home Page although it is a site for chironomid biologists and can get a bit techical. There are many species of chironomids ranging in size from very small to very large and species life cycles and life history patterns are all different.

If you saw "swimming" (and Roger provided the correct description for swimming) versions they were larvae. Also, check out Roger's site as he has listed some excellent references that are fly fisher friendly e.g. McCafferty's book, with regard to learning about aquatic insects. I can also recommend Merrrit and Cummins as another good reference.

Rick