Question re Microns and Hellgrammites

I have been spending some time with the various books out on Fly Fishing Entomology. It is now time for me to begin collecting and studying insects that reside in the local rivers and streams. I have noticed that there are two size kick nets 150 micron and 500 micron. I have called the companies and can not seem to get a definitive answer about which net I should purchase. I would like to capture as many things to look at as I can. However, I still don't know if the X number microns is the number of holes per inch or the size of the hole.

Also, on my tail waters, there are a lot of hellgrammites. What fly is this the nymph of?

Ken-

Microns refers to the size of the mesh. For example, 500 micron mesh would be 0.5 millimeters (1 micron = 0.001 millimeters), or would have approximately 50 holes per inch (1 inch = ~25 millimeters). In other words, the theory is that anything smaller than half a millimeter would escape through the mesh. As a practical matter, you’re unlikely to even be able to see anything much smaller that 2 millimeters anyway. If it were me, I’d go for the 500 micron mesh.

Hellgrammites are the larval stage of dobsonflies.

Sincerely,
Roger

Created: 08/22/2005 Last modified: 08/25/2006 www.FlyfishingEntomology.com