water beetle

I've found a rather rare species of a water-beetle, Dytiscus marginatus; do you know it?

At a little distance they were very puzzling, looking more like a water-beetle grown fat and lazy than aught else.

Compare the antenn with those of the locust and water-beetle.

I was only nearly eaten up by the perch; and then there was a duckling after me and a horrid dragon-fly grub and a water-beetle.