Insects in the Garden 335 
upon injurious insects and thus help to keep them in 
check. . A gardener should learn to recognize these ben- 
eficial insects, so that he may preserve and protect them. 
Parasitic insects. Many garden insects are preyed 
upon by other smaller insects that feed upon the living 
tissues of their bodies. The large caterpillar that lives 
on the tomato (and sometimes on the potato) may often 
be seen with its back covered with small white oblong 
bodies that at first glance may be mistaken for eggs. 
These are the cocoons of the larvee of a very small fly 
(one of the Braconids). The fly punctures the body of 
the caterpillar and lays its eggs under the skin. Then 
the larve hatch and feed upon the caterpillar’s body. 
A caterpillar that has been thus parasitized often dies. 
Empty shells of plant lice (aphids) may often be found 
clinging to the leaves of plants. These have been de- 
stroyed by another kind of Braconid. The mother in- 
sect finds an aphid and forces her eggs into its body. The 
eggs soon hatch, and the larve feed within the aphid and 
kill it. The pupz form inside the aphid after it has died, 
and when the adults develop they cut a circular opening 
in the inclosing shell and fly out to lay eggs for another 
generation. Wherever aphids are abundant, the shells 
showing that the Braconids are at work on them can 
nearly always be found. 
The lady beetles or lady bugs. Most lady bugs (or 
more exactly, lady beetles) are very beneficial to the 
gardener. The adults are small, nearly hemispherical, 
and usually gayly colored with conspicuous spots. Their 
larvee somewhat resemble tiny alligators in shape and are 
usually spotted and covered with bristling spines. Both 
