Peatland wildlife
Water beetles
Water beetles are probably one of the most diverse groups of
insects in peatland pools. Two of the most conspicuous beetles
are:
| Whirligig
beetle |
 |
Whirligig beetle
Whirligig beetles range from 3mm to 8 mm in length and have
smooth shiny streamlined bodies. Groups of up to 60 beetles
can be found whirling around frantically on the surface of ponds
searching for prey. The middle and hind legs form flattened
paddles ideally suited to this high speed turning movement.
They can dive to chase prey or if startled.
Their eyes are divided into two parts, the upper part to see
prey on the surface of the water and the lower part to see below
the surface. They catch small insects on or just below the surface
using their front pair of legs.
Great Diving beetle
| Great Diving
beetle |
 |
| Great diving beetle
larva |
 |
The great diving beetle is one of the most ferocious predators
in peatland pools. The adults are dark brown with a border of
yellow around the edges of the wing cases, and between 30mm
and 40mm long. Females differ from males by the presence of
grooves along their back, which give them a less shiny appearance.
The larvae are also fierce predators and can be even larger
than the adults. The adult female lays individual eggs in small
incisions she makes in water plants. The eggs hatch into larvae
that must surface like the adults to breathe. A further link
to their terrestrial ancestors is the fact that the larva must
leave the water to pupate. As their name suggests these beetles
are capable of diving for prey or into the mud when startled.
They use their oar-like hind legs, which are covered in swimming
hairs, to propel themselves through the water. They will tackle
a variety of prey including fish, tadpoles and other invertebrates.
While normally resident in weedy pools great diving beetles
are able to fly and will move at night to new waters if food
is scarce or mild weather dries up their current pool. They
lay eggs on submerged pond plants from March to May, and the
larvae, which look very similar to centipedes, take almost a
year to develop. The adults can bury themselves in the mud at
the bottom of the pond during very cold winter weather.
