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permanganate of potash. The latter, however, must be used with caution, as
it is injurious to plants as well as to the delicate gill membranes of fish.

The common aphis is the most prevalent of insect pests attacking
surface plants. However, it is easily controlled with nicotine spray. The
leaf minor cuts devious paths through exposed leaves, but can be destroyed
with arsenate of lead spray. Lotus and lilies are sometimes infected by
stem borers. It is best to remove the infected leaves and destroy the
worms.

Mosquitoes and other flying insects deposit eggs in the water where
the larvae furnish excellent food for fish, newts, and frogs.

In this manner pools are serviceable in reducing these pests. Plants
purify the water, while the fish help to keep the plants fertilized and free
from destructive insects. Water snakes, turtles, crayfish and fish-eating
birds are destructive. Some kinds of native fishes cannot be kept with gold
fish. Small tropicals, however, found in Florida waters, do well in pools.

A garden pool requires little care. In its construction, a drain is
convenient but not essential. With proper balances of plant and animal life,
the water will not have to be siphoned out more often than once a year.
Fish, however, will not stand alkaline water.