Midge head?

[Olympusman]

I'm finding these wrigglers in pond samples rich in midge larvae. They are from 8 to 14mm long and have six legs, so they are insects, possible the stage between larvae and growing wings and surfacing to fly.
This stack is hot with a 5X Swift objective and is a 121 shot stack stacked in Zerene.


A few notes on specimen preparation. I isolate the specimen in a small plastic cup and flush it several times with a pipette and clean water to wash off any particles clinging to the subject. Then I replace the water with fresh water and flush it again. I draw off the water and replace it with 10% grain alcohol to slow down the subject. (Everclear is a 95% grain alcohol sold in the United States at liquor stores).
After ten minutes I draw off the 10% solution and replace it pure grain alcohol.
I let the specimen dry completely before photography. When I am finished with the photography I preserve the specimen with Canada Balsam and a cover slip.

[Ichthyophthirius]

Hi,

This looks like the head of a damselfly larva. You'd need to show us the whole animal to make certain.

It's a nice image. One suggestion: You can anaesthetise gill-breathing aquatic insect larvae easily by placing them in sparkling water. The CO2 in the water knocks them out. Then put them back into normal water to take images and they will slowly recover.

That has the advantage that legs and antennae are in their natural positions and not contracted!
http://www.wattylereducation.info/index ... cleid=3308

[Olympusman]

Thnaks. Sounds really good. I'm finding some interesting water mites that I will try this on as well as larvae.

[Jacek]

beautiful pic

[Olympusman]

Thanks, Jacek.
My main scope is an old Swift M-3300 that was surplus from a community college. I had been struggling with the crappy field condenser on this thing for a couple of years. Last week I remembered I had a field condenser from an Olympus BH-2 stand that I bought for the focusing block to do stacks, so I replaced the Swift condesner withthe Olympus and I'm in absolute heaven. Three times brighter at least, better image sharpness and contrast and I'm able to stop down on the condenser far lower when using darkfield stops.

[Olympusman]

I got some more samples from a pond dip and it is indeed a damselfly nymph. I did some reserach and the nymphs go through several molts as they develop. The gills are the hairs on the end of the abdomen. I have an early stage nymph in seltzer water right now that does not have the gills, so we'll see how the CO2 trick works.
The CO2 does asphyxiate them for a while, but when they get into fresh water they start moving and their mouth parts open as if they were gulping. I had a group of specimens in changes of seltzer overnight, and some still resuscitated themselves, so I may try putting them on a slide in flat seltzer and see if that works.