mechanics of an inquiring mind, who keep fresh-water aquariums and
replenish them from ponds and brooks at "weekends," few persons outside
the fancy either see or know much of the water insects,[1] or are aware,
when floating on a summer day under the willows in a Thames backwater, of
the near presence of thousands of aquatic creatures, swift, carnivorous,
and pursuing, or feeding greedily on the plants in the water garden that
floats below the boat, or weaving nests, tending eggs, or undergoing the
most astonishing transitions of form and activity, on or below the
surface. Many of them are perhaps better equipped for encountering all the
chances of existence than any other creatures. They can swim, dive, and
run below water, live on dry land, or fly in the air, and many are so
hardy as to be almost proof against any degree of cold. The great
carnivorous water-beetle, the dytiscus, after catching and eating other
creatures all day, with two-minute intervals to come up, poke the tips of
its wings out of the water and jam some air against its spiracles, before
descending once more to its subaqueous hunting-grounds, will rise by night
from the surface of the Thames, lift again those horny wing-cases, unfold
a broad and beautiful pair of gauzy wings, and whirl off on a visit of
love and adventure to some distant pond, on to which it descends like a
bullet from the air above. When people are sitting in a greenhouse at
night with no lamp lighted, talking or smoking, they sometimes hear a
smash as if a pebble had been dropped on the glass from above. It is a
dytiscus beetle, whose compound eyes have mistaken the shine of the glass
in the moonlight for the gleam of a pond. At night some of the whirligig
beetles, the shiny, bean-like creatures seen whirling in incessant circles
in corners by the bank, make a quite audible and almost musical sound upon
the water. The activity of many of the water insects is astonishing.
Besides keeping in almost incessant motion, those which spend most of
their time below water have generally to come up constantly to breathe.
Such are the water-bugs, water-scorpions and stick insects, which, though