Lets Talk Bugs
by Tom Lager

Over the last few weeks I have noticed a number of different adult forms on the wing over some of my favorite trout streams. Up on the Little Wolf “Stenonema-like” mayflies were swarming in small numbers and occasionally a female would dive-bomb to the river surface and lay eggs. No fish were near enough or interested enough to rise to the occasion.

Examining submerged objectives for bugs revealed some interesting filter feeders – Brachycentrus (caddis larva) and Simuliidae (blackfly larva). Undoubtedly this is a good time of year for them; the algae are growing well and are becoming entrained in the drift for subsequent straining-out as a food source. My pictures of the bugs are not as good as I expected, but they give you an idea of what to look for in the stream. Brachycentrus larva attach there cases to a stable substrate with the open end facing into the current (notice the case attached to a small branch). At times I have observed as many as 18 to 36 cases on a branch.

The blackfly larvae curled up against the branch or rock they are attached to as soon as they a lifted from the water (see in picture below); however, when in the stream they attach their back-ends to the rocks and filter with appendages attached to their heads.

Both of these bugs have a low energy food gathering strategy – they just hook-up to something stable a hang-on. Note, these bugs will be found in flowing water, since they depend on passive-filtering. These caddis larvae attach their case to sticks (like above) with a small amount of silk, that they spin themselves. In fact they use silk to “glue” their bits of wood and debris together to form their cases. The blackfly larvae attach themselves with silk to rocks and such, but in a different manner. They apply silk to the rock surface to form a mat, then they sit on the mat and engage a myriad of micro-hooks at the end of their abdomen into it – this forms a very effective anchoring station. Are not these absolutely wonderful critters just Heavenly?

Now that you know what blackfly larva look like, you can get them in the stream before they emerge and feed on your blood. At times I’ve pulled branches from the stream that are completely covered with a dense coating of blackfly larvae.

 In the next weeks I am looking forward to sulphurs (Ephemerallidae) and hex (Hexagenia limbata). But I must admit I am having great success with Pass Lakes and brookies.

 Remember as you traverse our God given streams in search of trout, ”take the time to pick up the rocks and look at the bugs”.

Tom Lager