30 
PLANTS AND INSECTS 
is honeydew, for they like to feed upon this sweet fluid. Ants like also 
to attend the little creatures' that produce this fluid, and for this reason 
the aphids are sometimes called ‘ ‘ ant-cows. ’’ The milking of the cows 
is readily observed. An ant will gently stroke one with her feelers, 
and the little cow in response emits tiny droplets of honeydew from 
its tubes, which the ant eagerly licks up. Some species of ants think 
so much of their cows that they preserve the eggs of the little creatures 
in their nest over winter and carry the newly hatched aphids to their 
food-plants in the spring. 
These little cows are members of a large, family called Aphididae, 
or plant-lice. They live on the leaves, bark, or roots of plants, or 
inclosed in galls. The largest of them is only about one fourth of an 
inch long, and yet some of them lay eggs that can be seen with the 
unaided eye. 
An interesting study is to gather in the month of October cherry- 
twigs on which these little aphids are found. Freshen the twigs by 
keeping them in water, and soon the aphids will gather about the buds 
ready to lay their eggs. These they usually deposit in the angle between 
the bud and the twig. At first the eggs are yellowish-green bodies, 
oval in shape, but later turn to shining black. In the spring these 
eggs hatch into tiny black wingless females.. In about two weeks these 
give birth to living young that in a few days begin producing young 
also. Then comes a generation with wings. These leave the cherry- 
trees for other plants. In the fall winged females return to the cherry- 
trees, lay their eggs, and the year’s cycle is completed. This story is 
the life story of most of the common species of aphids. 
Many of these aphids cause the plant leaves to curl; others form 
galls on the leaves or stems. Besides this, they suck nourishment from 
the plants, and injure them with the honeydew, for this forms good 
“ground” in which various mildews and molds can, live. 
One way of ridding the plants of these pests is to spray them 
with various emulsions. Then, there are natural enemies to be en¬ 
couraged. These are the lady-beetles, dressed in their orange-yellow, 
black, and red. But one of the most interesting of the enemies for 
children to study is the little parasite Aphidius. Late in July up until 
October if you examine colonies of plant-lice you will find some of a 
lighter color than the rest and much swollen. Put a number of these 
in a glass, covered with a' gauze, and in a few days you will find neat 
