Beetle bait

Look at me, sitting here typing on my lunch break. You see the problem is all this stuff is too interesting. I could be jogging round the campus or reading the news or gossiping or something. But those things pale compared to excavating interesting plant / animal information from the internet. This is today's random find. It's from the Journal of Entomology and Natural History and is an idea for making pitfall traps for beetles.

Oh yes you may have done pitfall trapping before. But have you baited the traps with disgusting yet irresistible beetle-bait? I think not.

gravity-defying illustration from the article

The idea is that you put the stinky delicious things in a bottle, and you hang it above your ground-buried traps. That way the smell lures in creatures, but the traps are not contaminated by decaying goo. That way you don't have to scrape decaying goo off your specimens. If you even had any specimens left after larger creatures were drawn in by the smell and ate them. So this seems like a better idea. Have a look at the article for more detail.

The author, C R Turner, tried two recipes. One was made from melon, apple and banana left with sugar and baker's yeast in a sealed container for a week. Mmmm. That was apparently successful in attracting (amongst others):
Dorcus parallelipepedus (L.) - Lesser stag beetle
Carabus violaceus L. - Violet ground beetle
Carabus intricatus L. - Blue ground beetle
Serica brunnea (L.) - Brown chafer
and Trypodendron domesticum (L.) - Ambrosia beetle

The other was even more stinky, consisting of fish heads and chopped bones. But the beetles loved it and it pulled in:
Nicrophorus humator F. - Burying beetle
Nicrophorus vespilloides Herbst. - another Burying beetle
Thanatophilus rugosus LL. - another Burying beetle
Omosita depressa L., - another one
Geotrupes stercorosus (Scriba), - Earth boring dung beetle
Margarinotus cadaverinus (Hoffm.) - A clown beetle
and various others.

Pitfall traps are likely to catch beetles that have a quite active wandering-around lifestyle. But you can see how different bait attracted a different range of species. Some of them were really rather unusual, to the point where you might want to let them go, not despatch them. But it would be very good to know that you'd found them and where. Your local beetle recorder would be very interested.

To return to my previous typing about etymology, it's also rather interesting to see all the death-related words in the scientific names of the second group.

If you want to try pitfall trapping it's worth bearing in mind that the article suggests using ethylene glycol. But that's poisonous to birds and mammals and doubtless frogs and newts. And you wouldn't want to kill any of those. So you could just try using a little bit of water with a tiny bit of washing up liquid (the latter to break the surface tension). That'll probably be sufficient to capture and kill the beetles, and if you check the pitfall traps often, you can hoik out your specimens and put them in a pot with some invertebrate preservative. Or as you'll probably want to pin them, you might not want them wet in the first place. So it's not a bad option to avoid the liquid altogether, and just check the traps daily to pick out what you've caught (but they may eat each other first. If they haven't eaten each other, you can free any creatures you're not interested in). You could pop in a bit of leaf litter for somewhere to hide. And for a fancier trap you can have a grid over the top that stops large things getting in. There are many options. But whatever you choose, remember to collect all the cups at the end of your trapping, so they don't kill things indefinitely in a decidedly anti-conservation fashion. I'll let you decide what to do with your stinky trap bait.

The rather lovely Nicrophorus vespilloides. CC image Evanherk.

 Nicrophorus beetles are interesting despite their unsavory corpse-eating behaviour - they are a rare example of insects that show parental care. You can read all about it (along with humorous illustration) on Wikipedia (although once your interest is piqued there seem to be quite a few research papers discussing it).