April 19th, 2006
evening visitor
While walking across the front lane last evening, I spotted a dark, glistening oval-shaped object next to one of the tires on our van. I had a pretty good idea of what it was — a Predaceous Diving Beetle (Family Dytiscidae) — so I ran indoors to grab my camera and flashlight.
This large insect measured a total of 38mm in length (about 1 1/2 inches). It was mostly black, but its pronotum and elytra (wing covers) were edged with golden yellow margins (see above and below photos – click on images to see larger versions). It remained quite still while I shot several photos, but then did begin crawling forward. Its motion when on the move is interesting. The hind legs are long and curled as they are more suited to swimming than walking, so they appear awkward when the insect is on the move, making it look rather like a person crawling along on hands and knees. Walking probably isn’t something that these beetles ordinarily choose to do. They are quite capable of flight for getting from pond to pond. I shot a brief movie clip of the beetle for anyone who might be interested in seeing how this beetle moves when on land (1.1 MB and no soundtrack).
As their name implies, Predaceous Diving Beetles (Dytiscidae) are aquatic insects that hunt and dine on other creatures such as aquatic insects, tadpoles and small fish. A couple of years ago, I collected a few aquatic insects to study and photograph. The project soon became a study in which creature would outlast all of the others in the aquarium. It’s definitely a dog-eat-dog world when it comes to aquatic insects (which is also quite true of the insect world in general).
I’m not sure of the species of this insect, but it could be Dytiscus dauricus which seems to be considered common and with a very large range. Here’s a reference for this species on the University of Alberta’s online collections for the E.H. Strickland Entomological Museum.
NOTE: See comment below from Edward Smith who keeps several species of water beetles. He believes the one in these photos and video clips may be a Dytiscus marginalis water beetle.
I collected the beetle to keep overnight and will be attempting to photograph it swimming in a small aquarium before releasing it today. If I get any decent photos, I’ll post a follow-up sometime soon.
Tags: Dytiscidae, Dytiscus dauricus, Predaceous Diving Beetle
April 25th, 2006 at 3:19 pm
Can they fly?
April 25th, 2006 at 3:32 pm
Aydin – Yes, actually, they are pretty good fliers. I’ve seen them flying around the big lamps in parking lots at night. Quite impressive and give some people a good scare. They travel by wing to get to new ponds in search of suitable food and habitat. There’s a short bit of info on Dytiscidae on this page along with mention of their flying abilities.
http://collections.ic.gc.ca/biodiversity/family/Dytiscidae.html
January 24th, 2007 at 4:35 am
I live in Kuwait an di am a first grade teacher. As i was walking into school, i found this beetle. Amzing discovery. So beautiful. I was wondering is there a way to keep hi alive? Thanks for your reply.
January 24th, 2007 at 11:50 am
Jeanne – If it is a water beetle of some kind, you could probably keep it alive by putting it into some kind of aquarium or other container. However, you would need to cover the top with a piece of screen or the beetle will climb out and fly away. The bigger problem is what to feed the beetle as they eat things like minnows, tadpoles, other aquatic insects, etc… I had a couple of these beetles in an aquarium one time and they ate almost everything else in the aquarium in the space of a week!
June 19th, 2007 at 7:16 am
I believe this to be a Dytiscus marginalis water beetle. The video was great!! next time try adding in a stickle back or wounded minnow, these beetles can smell dinner very well. I raise them in my home and presently have around 11 different species. they are remarkable creatures. thanks for putting inforamtion and video out there for everyone to enjoy.
June 19th, 2007 at 7:26 am
Hi Ed – thanks for the note on the identification. I’ll make an edit to the main text to include this information. Yes,I’ll bet that would have made quite a different video if I had have added a minnow to the container!