Dry Mounted Insect

[Bryan]

I've been toying with this idea for a "permanent" dry mount for a while. I'm not really sure how permanent this one will be, I didn't do any preparation on it besides the fact that it was trapped in my wood burning stove and had dried out on its own. I guess time will tell. I didn't use my stove this winter, it wasn't very cold and never lost power this winter. It was trapped in there with a yellow jacket and a stink bug, they must have come down the chimney, the door seals pretty good. The yellow jacket and the stink bug are too big for a mount like this.

I found these fiber gaskets or washers at my local hardware store and they are almost a perfect size. They are 1/16" (1.6mm) thick and 3/4" (19mm) diameter. First I sealed the gasket to the slide with synthetic Canada Balsam. After that dried I placed the insect in the well and sealed the cover slip to the top of the gasket. After that all dried I sealed it with black acrylic paint on my slide ringing table. I probably should have cemented the fly to the glass slide but it seems to have stayed put quite well, it fits so perfectly. A smaller specimen will need to be attached. I know this is going to be fragile with just the cover slip on top so I have to be careful of getting objectives too close. I considered flooding it with Canada Balsam or something else but that seemed like it would have problems with drying and bubbles. I have seen slides like this made by putting two concave well slides together, that looks more durable. I may try that with the proper size specimen.

Anyone have any idea what this insect is? I was thinking some kind of Mayfly but those antennae seem kind of unusual. I assume it got that downward bend from drying out. I live in the Pacific Northwest near Seattle.

[Peter]

Hi Bryan,
It is some type of wasp.
Peter.

[TonyT]

Excellent. Just one suggestion. Over time the oils/fats in the wasp will vaporize and condense on to the cover slip; a slow process but you would likely start seeing it on the coverslip within a year; it gets worse!
The solution is to mount the coverslip with a water-soluble glue so that when it gets cloudy, and it will, you can replace it with a clean slip.

[Bryan]

Hi Bryan,
It is some type of wasp.
Peter.

Thanks Peter! I did a little more research and I think it may be a Scambus Wasp, a type of parasitic wasp. I did find an obscure article that lists them as native to the Pacific Northwest, but they do not seem to be common here. It's very hard to find any other reference to them in this area. They are mostly in Europe, Turkey and South America.

[Bryan]

Excellent. Just one suggestion. Over time the oils/fats in the wasp will vaporize and condense on to the cover slip; a slow process but you would likely start seeing it on the coverslip within a year; it gets worse!
The solution is to mount the coverslip with a water-soluble glue so that when it gets cloudy, and it will, you can replace it with a clean slip.

Thanks Tony, that's what I was afraid of. Maybe I can remove the cover slip with some Xylene when the time comes. I wonder if the addition of a desiccant inside the slide would help.

[TonyT]

A desiccant would not help, no effect on the lipids; would cause more problems.
If the insect is dry when mounted then moisture not a problem, cell is sealed.
Another way would be to remove all the lipids before mounting, soaking in acetone (or something similar) for about 24 hrs would work. Acetone is the standard method for dehydrating and removing lipids from Odonates.

[Bryan]

A desiccant would not help, no effect on the lipids; would cause more problems.
If the insect is dry when mounted then moisture not a problem, cell is sealed.
Another way would be to remove all the lipids before mounting, soaking in acetone (or something similar) for about 24 hrs would work. Acetone is the standard method for dehydrating and removing lipids from Odonates.

Thanks for that Tony. Will that be non-destructive to things like wings? I have done maceration of insects, but as I understand it the wings need to be removed and then re-attached for mounting because they dissolve in the caustic solution.

[dedalus]

I'm totally unskilled mounting permanent slides but i'd wish to note that i have succesfully mounted first time a small insect on a ringed slide just dehydrating it on a single step on 96º ethanol and not dry but in low end pva children's glue. Perhaps somebody more skillful in this may explain if some variation of this may be a preferred amateur method compared to dry mounting.
I think is very easy to do and dissecation without any fluid replacement may distort the subject too much, as well as move inside the cavity or have some long term access to oxygen for degradation? Maybe there is some optical reason why it would be preferred?

[BramHuntingNematodes]

Dry mounts are good for low power observation. The optical reason you might want a resin or wet mount might be to maintain more homogenous optical medium when using immersion oil. Also, especially for in vertebrate skeletons, chemical processing can allow for flattening, and scopes love a flat subject.

I use limonene for dewaxing, but I haven't made dryounts that way. Limonene is a little greasy. Xylene might be used instead of acetone, as I know it has some favor among arthropod enthusiasts, but is more toxic than acetone, which is a relatively safe solvent.