Permanent slide preparation of whole mount insects Part 1.

[AntoniScott]

My main interest in microscopy at the present time is making permanent slides of insects. Most large insects have dark brown or black exoskeletons that require further processing to make suitable permanent slides. Without this processing, their dark exoskeletons prevent examining their external and internal structures under normal light transmission viewing conditions.

Since I haven't found any books on whole mount permanent slide preparation I thought I would share my experiences with others on this web site forum. About sixty years (1962) ago a highschool friend of mine and I found this book in the school library which explained the process but I haven't seen that book in ages.



The insect is submerged in a bath of potassium hydroxide (potash) for an unspecified amount of time until the exoskeleton is semi bleached and softened. This endpoint should be determined through trial and error as blacker/bigger insects will require more time that say a brown beetle or a mosquito. Although I have read that a concentration of 10% is recommended I have found this to be insufficient. I prefer to make a saturated solution. The Potassium Hydroxide flakes, or pellets, are slowly added to the water and stirred. The large amount of heat produced could crack a glass container if too much is added at once.

After processing, the insect can be removed to a container of water approx 7"x8" in dimensions and an inch deep. This will allow manipulation of the insect under water so that limbs do not collapse, etc. A pair of flat ended tweezers can be used to squeeze the abdomen of the insect to remove the internal fluids which usually expell abruptly.

If it is determined by visual inspection that the insect is not sufficiantly "bleached" it can be returned to the potassium hydroxide for an additional amount of time. However, there are instances where the bleaching will not improve even if extended bleach times are employed.

Recently I discovered from a colleague in Great Britain that slide making entomologists further bleach exoskeltons,if required,in a 3% solution of hydrogen peroxide. Extreme care should be used with hydrogen peroxide as it is very easy to "over-bleach" if left too long. This cautionary timeperiod is in minutes, not hours or days.

[dtsh]

The Insects and Arachnids of Canada, Part 1 gives some methods. My copy was fetched some somewhere on the internet, AAFC_insects_and_arachnids_part_1_eng.pdf
It's a subject I haven't explored much myself yet, so I can't offer any personal experience.

[tgss]

Terrific reference AntoniScott. Thank you very much!
Tom W.

https://esc-sec.ca/wp/wp-content/upload ... _1_eng.pdf