Beware! Stag beetle larvae predator: click beetle larva!

Good decayed log is a must for most stag beetles if you want to achieve a maximum number of larvae from your stag beetle female. The majority of females would always prefer to lay their eggs into the log instead of laying them into a layer of compacted substrate. If you collect your log from the woodland, there is always a chance that other critters will be living in it. General recommendation to get rid of these is to soak the log in the water for about three days. However, I found that  is often not enough to kill all of them. Thicker logs take more than a week for water to completely soak through the whole log. The other way to destroy things in the log is to heat it, which is often not very convenient. Low temperature long time dry log baking in  a family kitchen oven can be tricky:) More recently I adapted the way of preparing logs by sawing them into shorter sections, so they could just fit into a microwave. Using a microwave 15cm-diameter log can be heated through completely in two 4-5 minutes steps with very little effort. The time needs to be increased for bigger logs.

In my earlier breeding experience, I often would use decayed logs with only short term soaking in water or even without any preparation and most of them would work fine. However, on a number of occasions I discovered that the number of larvae obtained from stag beetle female is smaller than expected and at the same time I found some other beetle larvae in these logs.  Although  many critters such as longhorn beetle larvae are completely safe for the stag beetle larvae, the other critters may not be as safe. Particularly, and I learned it in a hard way, click beetle larvae can hunt and eat stag beetle larvae. And this is not an assumption, while splitting logs when looking for larvae I found click beetle larva eating still semi-alive stag beetle larva. Moreover, if you use chunk of such wood as a decorative top piece in breeding box for any sort of beetle such as rhino or flower beetle, the click beetle larvae can come out of the wood and live in the soil hunting newborn larvae or eating freshly laid eggs. Here are some photos and video of a typical click beetle larva which, hope that you will find it helpful. If you see anything like that in your wood/substrate remove it and sterilize substrate/log by heating it.