Live adult vi
A large hole in a fruit, seed, nut, twig or trunk generally indicates where the insect has come out, and not the point where it entered.
The chief groups of internal feeders are indicated by their common group names: borers; worms or weevils in fruits, nuts or seeds; leaf miners; and gall insects.
Adults have fully developed wings and can fly great distances.
Nymphs either do not have wings or have wings that cannot be used for flight. Perhaps the best way to gain an idea of the prevalence of this type of insect damage is to try to find leaves of plants with no sign of insect chewing injury.
Figure VI-2 depicts the developmental stages of insects with incomplete life cycles. Another important method which insects use to feed on plants is piercing the epidermis (skin) and sucking sap from cells.
The attacks differ from the above ground forms only in their position with reference to the soil surface.
Some subterranean insects spend their entire life cycle below ground.
Control measures for internal feeding insects are most effective if aimed at adults or the immature stages prior to their entrance into the plant.
A number of internal feeders are small enough to find comfortable quarters and an abundance of food between the upper and lower epidermis of a leaf. Gall insects sting plants and cause them to produce a structure of deformed tissue.They gain entrance to plants either in the egg stage when the female thrust into the tissues with sharp ovipositors and deposit the eggs there, or by eating their way in after they hatch from the eggs.