Giant Water Beetles of Doom!

Sorry I've been neglecting this blog so much. I am become busy at work, such that I'm putting in 40 hours per week just on lab work. Email, reading papers, and other non-lab-work-but-still-work stuff is on top of that, and I've been pretty tired. But, tonight I find myself able to justify a little time here, so I thought I'd let people know I'm still alive, and show you something I've been working on.

My PhD project could easily become too broad and unmanageable, so I'm going to focus on a few key groups of invertebrates in which to study evolution, genomes, and climate. One of these is the beetle family Dytiscidae, the predacious diving beetles.

Dytiscids (pronounced either die-tiss-id or die-tisk-id) are the most aquatic of all beetles - at least, according to the people who really, really like dytiscids and spend their careers studying them. In any case, close examination of a diving beetle will show their streamlined, hydrodynamic shapes, their powerful swimming abilities, and their highly modified life cycle. They're also among the largest insects, though the variation in body size in the family is very high - some are orders of magnitude larger than others.

It's this last point I'd like to emphasize. While most of the species of dytiscids I've met so far, around Guelph and in Churchill, were sort of normal beetle-sized (i.e. about a centimeter long), I've met a few that were much smaller (2-4 mm long) and, very recently, some much, much larger ones.

When I cleared my bottle traps yesterday, I found staring back at me through the clear plastic walls, the largest insects I've ever seen (Fig. 1). I threw one on the lab mass balance; it was moving around, so the precision of the machine was a little low, but it came in at about 2.75 grams. For a beetle, that's freakin' huge. I'm a little afraid of these guys - I caught about 20 that size - because they're predatory and have been known to bite people. Not that there's any real danger, of course, but descriptions I've seen suggest such bites from large dytiscids are a bit more painful than a bee sting. Something to avoid, obviously. The other reason I'm afraid of them is their lack of food-satiety. In other words, experiments by beetle researchers have shown that there is nothing you can do to make a dytiscid feel "full" - they'll keep attacking and eating prey as long as it's available, regardless of how much they've already eaten.

Fig. 1. Giant Dytiscid of Doom! Note ruler - this beetle is three centimeters long. Trust me, that's a big beetle.

Anyway, I got these guys back to the lab, then had to figure out what to do with them. I had the 'genome machine' booked for that time, and competition for access to the genome machine is rather intense so I couldn't just abandon that and play with beetles. I quick-processed a few (i.e. dropped them in dry ice) and put the healthiest 10 individuals into individual tubes (so they wouldn't eat each other) and put them in the 'fridge. I've been replacing their water and air every day, until I have time to work on them - that'll be tomorrow, since I was also signed up for the genome machine all day today.

If my feeble attempts to shock you with giant insects haven't yet worked, consider the following: dytiscids are excellent, powerful fliers, and they release truly foul-smelling chemicals when stressed. Stinking, ravenous, flying insects! Aaah!

Fortunately, the 'fridge and current weather conditions both seem to be keeping their wings covered. If the 'fridge fails, though...