280 
ELEMENTARY AGRICULTURE 
the plant. After a few weeks, the larva changes into a 
sort of ball known as a pupa or resting stage. The pupa 
remains in the bolls from three to five days, when it 
again hatches into the adult. Eggs are laid and the 
same forms are developed as those shown above. A few 
of the adults survive the winter and lay eggs the next 
spring. Many plans have been suggested for destroying 
the boll weevil, but none has been entirely successful. 
Poisons have been used at the time when the squares 
were forming. A heavy spray or dust of arsenic prepara¬ 
tions seems to protect the cotton plants from serious 
injury. 
The Cotton Boll Worm, the red spider, the leaf roller 
and many other insects attack cotton. 
Plant Lice are very small insects found upon a great 
number of plants. They are often called aphids. You 
may find them on rose bushes or house plants, where the 
tender leaves begin to come out. The plant louse attack¬ 
ing cucumbers and melons is known as a melon aphis. 
The aphis has a very interesting relationship with 
small red ants. During the fall, the ants collect the eggs 
of the plant louse and take them into their homes under 
the ground, where they are kept during the winter. In 
the spring, you may observe the ants carrying the aphis 
eggs up the stalks of corn or grass. When the plant lice 
hatch, they suck the sap from the plant and make a 
kind of honey which the ants use for food. These may 
be observed about the growing stalks of corn. Thus the 
two insects work together to secure food. 
Scales.—Nearly all fruit trees and many kinds of 
shade trees are attacked by insects known as Scales. 
Dead branches of a tree often are covered with white, 
scale-like forms. These are the shells covering very 
small insects which suck sap from the tree. A great 
