Altica palustris?

[rowanalder]

I seem to be building up quite a collection of insects which require dissection for identification. Will give me some practice. Would it be possible to use relaxation fluid, I know the rest of the insect would become relaxed but would it help with dissection of dry insects?

I will keep my eyes peeled for anymore of these guys and hopefully find a male. I couldn't make my mind up whether this was a male or female, the tarsi segment looked swollen but not by much, I could not tell if this was normal sized or swollen.

Thanks,

Ro

[Klaas Reißmann]

Hi Rowan,

it is a female.

For dissection you should relaxation fluid. If you don't the beetle will break and gets totaly damaged. You need to prepare it completely new. Make it real soft by using relaxation fluid and pull out the Spermatheka. Problem is, that I don't know a good key for the ID of the Spermatheka, so a male would be better. But males are very rare in many Species and I guess in yours, too (I have an idea which species it is).

Regards
Klaas

[rowanalder]

Hi Klaas,

Thanks for the info, I will buy some relaxation fluid. I will have a hunt around and see if I can find some information on identifying these beetles. There appears to be a page on the Watford Coleoptera Groups website on these beetles but the section is down at the minute.

What would be your guess on this one, wouldn't be palustris by any chance?

Thanks,

Ro

[Klaas Reißmann]

You can take 5% acetic acid. Buy some 25% acetic acid and dilute it down to 5% by using water. Or you can boil water up to 70 °C (not more) and put the beetle into the hot water for some minutes. It will get relaxed within a few minutes (just try) and can be dissected and prepared emidiatelly.

Regards
Klaas

[Jason Green]

5% acetic acid - try using table vinegar, or even pickling vinegar (10% strength). I've used that method, but prefer Klaas's suggestion of water. Much quicker, and is the way I dealt with that chrysomeloides prior to dissection.

[Klaas Reißmann]

Hi Jason,

I don't like table vinegar. Normally it is no clear fluid and the colouring of the vinegar sometimes injure the real colours, so I prefer the clear fluids, for example the essence of acetic acid (25%). But as you wrote: the water method is much faster.

Regards
Klaas

[Matt Smith]

In the UK we can buy 2 kinds of "ordinary" vinegar at the supermarket. "Malt vinegar" is dark brown and is the stuff you put on your fish and chips. "Distilled Malt Vinegar" is clear and is used when you don't want the brown colour - I use it for relaxing insects.

[Klaas Reißmann]

Hi Matt,

I guess if the Distilled Malt Vinegar is 25% it is what you can by in the supermarket around here called "Essigessenz" (essence of acetic acid). If it is 5% I guess it is almost the same, but cut back to 5%.

Sounds pretty much like that.

Regards
Klaas

[Jason Green]

Originally Posted by Klaas Reißmann

I don't like table vinegar. Normally it is no clear fluid and the colouring of the vinegar sometimes injure the real colours, so I prefer the clear fluids, for example the essence of acetic acid (25%). But as you wrote: the water method is much faster.

I don't use anything acetic now, just hot water. My field-seasons are too busy to be working a 'week in arrears'.

[rowanalder]

Hi Guys,

Had another look at work yesterday but found no beetles at all. But did get presumably Mesembria meridiana (Don't know if there are any similar looking species in the UK). Plenty of what appeared to be more Eristalis tenax.

Thanks for the info, I used some distilled vinegar last night on some specemins that I found in Europe last year, and it worked well.

Thanks again,

Ro