Naturespeak A naturalist's view of the world

October 29, 2009

A Beetle to Die For

Filed under: Uncategorized — wykes @ 8:40 pm

I doubt that any kids out there will be dressing up as a Predaceous Diving Beetle this Halloween. Apart from the obvious structural difficulties it poses as a costume, it is too obscure of a beast to qualify. And the name, well, that name is just not catchy enough. Albeit descriptive, it’s just a little too generic –  like calling a Tyrannosaurus rex a “Predaceous Walking Sauropod” or a Grizzly Bear just a “Large Bear.” These creatures have a semantic zing that places them in the spotlight as bad boys – big bad boys. The Predaceous Diving Beetle is a bad boy too, but it can’t get the press it deserves with a name like that.

Granted, you don’t see too many Halloween T. rexs or G. bears out there pounding the trick or treat circuit, but 4 out of 5 boys would be proud to dress as one or the other if the opportunity presented itself. I doubt your regular  little Timmy or Rebecca would find it exciting to declare themselves as a Predaceous Diving Beetle when asked at the porch. “A What?’, the befuddled candy giver would remark after acknowledging the clearly identifiable princess, devil, and hobo next to you.  “I said, I am a Predace..ous..oh, never mind. I am Dytiscidae, Lord of Aquatania.”  I am not speaking from personal experience here, but I can imagine such an occurrence. I remember “treating” once in  a homemade Big Brown Bat costume and recall the frustration of being variously identified as a pile of rags, a mouse, and a cat’s hairball.

The Diving Beetle is a creature worthy of the name Dytiscidae Lord of Aquatania. Perhaps we should launch a campaign to change the name.  These hefty aquatic beetles (see one in hand above) are members of the family Dytiscidae (I said “dy-TIS-ki-dee”). True to name they are predators which feast upon lesser life forms in our local marshes and ponds. They rank among the top predators in the aquatic world and are lords of their domain. Everything, well almost everything,  about them is geared to predatory performance.

These beetles are equipped with hollow needle-like jaws (see portrait above). When they grab prey, digestive juices are quickly injected into the quarry whose pulpy remains are then slurped up. While grizzly bears dismantle their prey from the outside in, the Lords of Aquatania (I said “a-kwa-TAN-i-a”) take care of their business from the inside out! In basic outline, you will find no sleeker creature than the PDB (aka D-LoA). It is made to cut through the liquid element without offering any drag. Every body segment fits neatly with the adjacent part to offer a seamless profile. It is difficult enough to hold onto one of these things when they are dry, leave alone when they are wet.

Diving beetles take in a bubble of air under those sleek wing covers to serve as an aqualung. They are air-breathers. The oxygen supply is refreshed on a regular basis by surfacing for air with the back-end directed first. Tyrannosaurus, as far as we know, took in their air front end first.

Perhaps the most remarkable features on these beetles are the highly specialized legs (see a full set here). In most swimming beetles, the legs are fringed so that they can perform as paddles. Indeed, the last pair of legs on the PDB are heavily fringed. These paddle legs are employed in unison, like the action of a sculling team,  to propel the insect forward in no uncertain terms. The second pair of legs have a fringe as well, but are also covered with dozens of little suction cups to provide grip on slippery surfaces and prey (see above). Male diving beetles sport a set of amazing suction cup apparatus (apparati?) on their first pair of legs (see below and detail here). These structures, looking for all the world like glass-handling suction cups,  serve to maintain a grip on slippery girl diving beetles when they mate. You’ll note the two large suction discs and the multiple smaller suction points needed to keep the female from breaking away during “the act.”

I must admit, all these specialized parts would be impossible to duplicate on a Halloween outfit, but wouldn’t it be great to have a pair of those sucker disc feet in order to plow into that dish of Snickers – emptying it with one swipe. Why, those other “regular” kids would envy you – you, the Lord of the Treat bowl. Should you attempt to make a Water Lord costume for your kids, it would be wise not to divulge the real purpose of  those sucker cup things until your children are well past trick or treating age.


  1. Wow, suction cups for breeding? That is scary! And big brown bat is an excellent idea for a Halloween costume, though I’m pretty set on going as Red Green! Um, not that I trick or treat any more. Or even have the right elements for the costume… but should I ever get it together enough to create any costume, it’s going to be Red! Um, happy candy day!

    Comment by Monica the Garden Faerie — October 30, 2009 @ 9:26 am

  2. Amazing photos – to accompany another stellar post! And now, with the challenge made, I just might have to contemplate making a PDB costume! HM…..

    Comment by Elln — October 30, 2009 @ 10:27 am

  3. Oh my gosh..I feel for you and your bat costume….What an interesting insect. I wonder if we have them in the pond or back in the wetland woods… Happy Halloween…. Michelle

    Comment by ramblingwoods — October 30, 2009 @ 10:50 pm

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