September 28, 2021

I, Science

The science magazine of Imperial College

Analyse your Christmas tree closely enough and you're likely to see hundreds of zombie bugs on them …

Tree Bug

Still think it’s just a mouse stirring on Christmas Eve? Think again if you have a live Christmas tree – they are crawling with life. Up to 25,000 creepy crawlies can be found in just one tree according to experts from the University Museum of Bergen, Norway.

Bjarte Jordal, an expert in tree-living beetles, is adamant that this is not at all dangerous or threatening, and also that there is not much we can do.

So what are these unwanted guests you invite in? They are a mixture of cool and creepy-sounding insects: springtails, moths and mites, so far so good, but bark lice, and possibly ticks sound less than pleasant. There is also the obligatory spider, probably eating all the other creepy crawlies.

Zombies? Really? Well, not quite, but they do go into a hibernating state during the winter, replacing all the liquid in their bodies with glycerol before re-awaking in springtime. Unfortunately for us, that response can be triggered by the warmth of a living room and many will come out of hibernation early.

But why can’t we see them? As most of the insects are in hibernation, they tend to hide in cracks in the bark and many are also camouflaged. Their size is also a problem – most are only just visible to the human eye. There is one way though, shake your tree over a large white sheet and you can see lots of small dark bugs dropping off, just be sure to take the baubles off first.

While it shouldn’t be much of a surprise, Jordal says we just don’t think about these sorts of things; we forget about nature, particularly when in our own homes. But don’t worry, none of these critters have been shown to be harmful, and as Jordal is careful to point out, without the moisture of other live trees “the bugs will quickly dry out and die.”


IMAGE: Wikicommons