Catch me if you can!

It’s been a while since my last blog post. In the meantime, I was very busy trying to find some suitable Common Cockchafer larvae for a field experiment. This search turned out to be much harder than expected. Larvae of the Common Cockchafer live in the soil for three years before they appear as full-grown beetles on the soil surface. During this time, they go through three different larval stages and one pupal stage.

Currently the only method to find cockchafer larvae is to take a spade and go digging. But of course, I cannot go around digging just anywhere. First of all, I had to find a field where a) Common cockchafer larvae were very abundant, and b) larvae had not entered the pupal stage yet. In addition, there was a bit of a time pressure because cockchafer larvae rest during winter and for this purpose they dig themselves deeper into the soil to escape freezing temperatures. “Deeper” can be as far as one meter or even more. After finding a suitable field site – and after obtaining the permission of the site owner to dig some holes – it was time for a late autumn field trip. The field site turned out to be a strawberry field. Common Cockchafer larvae love to feed on roots of strawberry plants, which of course, does not amuse the farmer because strawberry plants die when their roots are severely damaged. So it came as no surprise to hear from the site owner “You can dig out as many larvae as you like, as long as you never bring them back again.” And that was exactly what we did.

Created with Nokia Smart Cam

Created with Nokia Smart Cam

Created with Nokia Smart Cam

Without the help of my colleagues who kept digging despite the rain, cold, and mud, I would have never collected enough Common Cockchafer larvae for my field experiment. On the first day, we were two people digging holes for two hours and then I continued digging for four more hours by myself. That resulted in twelve larvae. A few days later, we returned with five people to the strawberry field. During five hours of digging we found 17 additional larvae. Quite elusive these little animals…

Created with Nokia Smart Cam

Found one!

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