Pressed Insects

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The above photo is of three older microscope slides I picked up via eBay for a few dollars. Whole mounts of this sort were once a lucrative business for optical and biological supply houses, and a thriving area of pursuit for hobbyists producing slides of their own. Inarguably, preparations of this sort are very striking under the microscope or even with the naked eye. They are also frequently criticized. Some entomologists, even some microscopists, both today and in the impressive body of historical microscopy and etymology literature, positively railed against slides of this sort. For some, the only proper way to mount insects or arachnids will always be on pin under glass. Why all the hate?; Maceration and pressure.

In order to mount an insect (or anything for that matter) on a slide there are really only two options; incredible thinness or a cell of appropriate thickness, and we wont be dealing with cells today. Some insects (or portions of them) are of a size that may be mounted intact without a cell, however, for the majority that is not the case and the specimen must first be somehow processed. For slides like the above, that processing involves removing all but the chitinous exterior of the specimen, rendering that chitinous skeleton pliable, flattening it so that no cell is needed, and rendering the specimen transparent. Doing so necessarily renders the specimen quite different from its natural state which can lead to false conclusions regarding the species, especially among amateurs.

While the scientific value of slides like the above is debatable, their appeal is undeniable. Some modern slides like the above are available, but they are generally no where near as plentiful, or as well prepared as they were fifty or more years ago. So, is the present day microscopical hobbyist limited to the dozen or so species that may be found from the modern suppliers or what may be scrounged up second hand? Of course not! With a few rather common supplies and a bit of patience one can produce pressure mounted insect slides of their own. After all, I’ve done it with perfectly passable results; and believe me, if I can do it, so can you.

In the next few posts I’ll be going through the process from collection to completion and pointing the way to some classic works that provide much more exacting procedure than I. 

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