not require that the water be changed more
often than once in two months.

Too much direct sunlight causes too rapid growth of green slime, hence
the aquarium should not be set in a window. Close to a window through
which the sun shines upon it for an hour or longer each day is the best
position.

Do not supply more food to the animals in the aquarium than they can eat
up clean.

Crayfish, perch, trout, and other freshwater fishes are destructive of
insect larvae and other aquarium specimens, hence care must be taken in
selecting the specimens that are put together into an aquarium.

Suitable animals for the aquarium: mosquito larvae, dragon-fly larvae,
caddice-fly larvae, crayfish, clam, water snails, tadpoles, fish, frog,
turtle.

AQUARIUM SPECIMENS

MOSQUITO

Time.--May or June.

~Questions and Observations.~--At what time of the year are mosquitoes
most plentiful? In what localities are they most plentiful? Why are
they most plentiful in these places? Are mosquitoes ever seen during
fall or winter? How do you account for their rapid increase in number
early in summer?

How do mosquitoes find their victims? Observe the humming noise and try
to discover how it is made.

Watch a mosquito as it draws blood from your hand. Does the point of the
beak pierce the skin?

Capture a number of mosquitoes and place them in a jar containing some
water and a few straws or sticks standing upright out of the water.
Cover the mouth of the jar with a glass plate or fine gauze. Watch for
the rafts of mosquitoes' eggs on the surface of the water.

The eggs may also be found on the surface of ponds or open rain barrels,
and may be transferred to water in a jar in the laboratory.

STUDY OF THE ADULT FORM

Note the shape, colour, sucking tube, wings, and legs. Compare with the
house-fly.

Distinguish the male insect from the female; the former has feathery
feelers, and has mouth parts unsuited for biting.

How many kinds of mosquitoes have you seen? Direct attention to the kind
which causes the spread of malaria. It is recognized by its habit of
standing with its body pointing at right angles to the surface on which
its feet are placed or, in other words, it appears to stand on its head.

THE DEVELOPMENT

Describe the egg raft.

Observe the wigglers (hatched in about a day); the divisions of the
body of the wigglers; position of the wigglers when at rest. Observe
that the tail end is upward. Lead the pupils to