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  • Dan Asaw

Customising Vane traps

Ok, so you have your vane trap ready to go, and you are chomping at the bit to see what you can find. But what about that collection chamber of yours?


leaving it empty is an option, assuming you are checking it daily, and don’t mind everything trying to escape when you open it.


Essentially you have a few options that fall into 2 main camps.


Live trapping and lethal trapping





LIVE TRAPPING


The main benefit of live trapping is that you dont have to kill anything, so you can release things afterwards if they are easy to ID or you just want to take nice photos ( great for things like outreach events)but this comes with a few downsides…

  • It has to be serviced daily to prevent things eating each other

  • It cannot be kept in open spaces where the sun will cook the occupants

  • Specimens try and escape when you open the lid

  • Specimens may die anyway due to the above factors or being stressed out

There are of course ways to mitigate these problems, assuming you are checking a trap daily of course (which is fine if its in your garden for instance).

These would include:

  • adding a substrate in the pot (sand for burying species)

  • Adding plant material to provide shade and hiding places

  • keeping traps out of exposed areas

Obviously if you were checking daily, I would recommend using bait of some description , this could be:

  • Aged chopped meat (watch out for wasps and use gloves)

  • fruit

  • sugar solution

  • a sponge soaked in beer

Personally I’ve had some great experience using vane traps to catch live carrion beetles, this was achieved by using aged liver (read: left in the boot of my car to sweat for a week), wrapped in a cheese cloth parcel and suspended in the collection chamber which was half full of sand (for the beetles to bury into.

Left for 2 nights I opened the trap to find not 1, but 3 species of Nicrophorus! N.humator, N.investigator and N. vespilloides! This was ideal as I was doing it for a public out reach event!




LETHAL TRAPPING

I must admit, this isn’t for everyone, but quite frankly sometimes live trapping just isn’t feasable- for example if you are trapping in a remote area, or cant access a place daily, its an emotive issue- one that i’m not even going to attempt to address here.

The basic idea is essentially, the collection pot is full of a chemical that will quickly kill the organisms that become trapped in it.

This can be advantageous because:

  • Nothing escapes so you get a good representative of species on site

  • things don’t eat each other (so important specimens remain intact)

  • It can be serviced much less regularly (intervals of several weeks)

The down side however is you end up with plenty of bi-catch, for example I’m a Coleopterist at heart, so really I only have the knowledge, resources and time for beetles, and traps like this will also catch lots of Diptera, Hymenoptera, Hemiptera and Collembola. I try and keep everything I can and distribute it accordingly (to those who specialise in those groups) but that does take up time, space and resources.


LETHAL TRAP PRESERVATIVES


There are several options for lethal traps, they are:

  • Water detergent mix

  • Isopropll alchohol

  • propylene glycol

  • Acetic acid (white vinegar) solution

  • Antifreeze

WATER DETERGENT MIX


This is water, with a drop of washing up liquid in it to break the surface tension (invertebrates tend to float otherwise)


Pros: it is dirt cheap, non toxic and easy to obtain, specimens are relaxed.


Cons: if its left for longer specimens begin to disintegrate (at around a week)


ISOPROPLL ALCHOHOL


Insects fall in, become intoxicated and meet their demise, it’s what the pros use as it preserves DNA very well. It can be found on Ebay and Amazon


Pros: Can keep specimens for a very long periods of time, can act as an attractant, inhibits bacterial and fungal growth. It can also be diluted.


Cons: It can be expensive, evaporates readily and is flammable, so may be fire hazard where it is stored, its also toxic, although not much will try and drink it as its not especially palatable. Can cause specimens to become brittle and difficult to relax.


PROPYLENE GLYCOL


This is my collection fluid of choice, I buy it in the form of ‘RV antifreeze’ which is bright pink, but it does come in clear forms as well, its used as a food preservative in industry, but its possible to pick it up on bay/Amazon.


Pros: Fairly cheap (£7 for 5 litres), non toxic to animals, dilutable (I use it at about 50% PG to 50% water), and can be left for a good few weeks before specimens start to look a bit ropey. Not too bad to obtain. Specimens are very supple and easy to mount directly. It also breaks down naturally in the environment.


Cons: not as effective as storing DNA, can get a sticky if not washed off work spaces.


ACETIC ACID


This was suggested to me by the NHM’s resident staph expert Roger booth. I haven’t got round to testing it yet, but dispite my reservations (as i was worried it would damage and discolour specimens stored in it). He seemed very supportive of it (and well, he is an expert, twice over after all). I use white vinegar all the time as a cleaner, relaxant and to some extent a storage method, so i have it all over the place.


Pros: super easy to obtain (in the vinegar aisle), cheap as chips (literally), non toxic, acts as an attractant. Specimens are relaxed and ready to mount


Cons: you smell like a chip, possible specimen degradation over long periods of time?


ANTIFREEZE


I think this used to be very common as a collecting fluid. I personally wouldn’t advise it partially because the non non-toxic stuff Is absolutely lethal to cats and dogs, not to mention all the other mammals that may come into contact with it), its not any cheaper than Propylene glycol anyway.

Pros: Easy to obtain, wont freeze, lasts for long periods of time


Cons: Can be wicked poisonous, not much cheaper than better alternatives, can make specimens difficult to mount directly. Not good for the environment if spilled

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