OND BUGS
"Ponds and streams are rich environments, home to many insects. Some, like the diving
beetles, spend most of their lives submerged. Others, like mosquitoes and dragonflies,
begin life underwater and then become airborne. Each species is fascinating in its own
way; but among them all, those belonging to the order Hemiptera, suborder
Heteroptera, may be the most intriguing."
— Roger Brunt, Nature Canada, summer 1989, p. 27
Watch any pond for a few minutes and you're sure to see a water strider,
backswimmer, water boatman or water scorpion busily swimming, diving, or
gliding over the water as it hunts for food.
Water striders
(Class Insecta, Order Hemiptera, Family Gerridae) literally walk on water (see photo, top left). Their extremely long middle and back legs spread their
weight over such a large area that they don't even break the surface tension. The
oily hairs covering their feet also help by acting like waterproof snowshoes.
Although you won't hear a water strider, watch for ripples as it stamps its feet to
announce its territory to any other striders in the vicinity.
Backswimmers
(Class Insecta, Order Hemiptera, Family Notonectidae) are powerful 12-mm-long bugs that swim around enveloped in a shimmering
cloak of trapped air. Backswimmers hunt on the surface like striders, but hang
upside down under the water (see photo below). Because of this, their colouring is reversed — their
backs are light coloured and the stomach side dark. They breathe air that they
trap between their wings and abdomen. This air also keeps them afloat as they
wait for flies or other insects to drop onto the surface of the water. Their painful
bite has earned them the nickname "water bee."
Water boatmen
(Class Insecta, Order Hemiptera, Family Corixidae) are similar to backswimmers in shape, although a bit smaller. Hairs on their back legs make them look like little oars that they use to maneuver through the water in a jerky movement. You usually see them
as they break the surface of the water to trap air under their wings and in the
thin layer of hairs on their stomach. The air bubble allows them to remain under water for a long time as they hunt for food — plant material, algae, and small larvae of other species.
In fall, boatmen swarm. They communicate by rubbing pegs on their forelegs against
sharp edges of their head to make a chirping sound that is species and sex
specific. Hundreds can be seen emerging on plant stems before taking flight, mating, and dispersing.
Water scorpions
(Class Insecta, Order Hemiptera, Family Nepidae) seem to move in slow motion as they creep and grope among twigs and stems
underwater. These bugs hunt using stealth rather than speed. They will hang on
to a stem 10 cm below the surface waiting for prey. Every so often they back up
the stem just enough to reach the surface with the long breathing tube (up to 50
mm) that protrudes from their abdomen. Like a snorkel, this allows them to
breathe while remaining on the lookout for food under water. Scorpions produce
a low chirp when they rub their long legs together.
This species of water scorpion is also called a water stick insect or needle bug.
Most heteropterans
can fly, but only do so on special occasions like seasonal migrations or to move to
a new pond if the water supply dries up. They find a new home by looking for
reflective surfaces as they fly. Sometimes, they mistake the shiny hood of a car or
a picture window for a potential habitat. Water striders hibernate away from
water, so they must "migrate" to and from their pond. But the most dramatic
events are the dispersal flights of the water boatmen. During the first warm days
of spring and again in late summer or autumn, there are so many water boatmen
coming and going, they make the pond surface look like it's raining.
Source for this material: Roger Brunt, Nature Canada, summer 1989, p. 27
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