Insect external structure
Insect internal structure
Development of insects
Relationships of insects
Leafhoppers and Treehoppers
Insect identification > Homoptera
The Homoptera is a large group containing insects of many forms, often showing little resemblance to one another. They suck sap from plants through a beak, apparently very similar in structure to that already described for the Hemiptera, but it is attached not to the front but to the hinder part of the under surface of the head which is very closely joined to the prothorax so that the beak frequently appears to arise between the front legs. In some instances where the adults do not feed, this structure is lacking.
The wings are often absent but when present are usually held, while at rest, sloping over the body like a house roof. They are of the same thickness and usually, though not always, transparent. In this group (except the male scale insects) the metamorphosis is incomplete.
These facts may be summarized as follows:
The Homoptera are sucking insects with the beak (when present) arising from the back part of the underside of the head which is very closely joined to the prothorax. The wings (frequently absent) are of uniform thickness throughout and when not in use are held sloping over the body. The metamorphosis (except in male scale insects) is incomplete.
Few groups of insects show as great differences in their members as are found here. The cicadas, often two or three inches in length and with a wing spread of 4 in. or more, are among the giants of the order, while some of the whiteflies and scale insects are hardly more than just visible to the eye.
Most of the group move about freely, though some locate in one place soon after they hatch and remain there the rest of their lives. In one section the insect produces a protective scale which covers it, and, beneath this, degeneration of some parts of the body occurs.
Many Homoptera secrete a sweet, sticky fluid called honeydew, often in such quantities, when the insects are in abundance, that in falling it makes a noise like fine rain. Striking on leaves, fruit or bark, it adheres and dries, and a blackish fungus grows in it, giving to such places a sooty appearance.
This secretion appears to be produced most abundantly by the soft scales, whiteflies, plant lice, jumping plant lice and some of the treehoppers. Ants and honey bees feed on the honeydew and frequently visit the insects producing it, for this food.
Nine families of Homoptera are generally recognized, but four of these may, for convenience, be combined here. The six to be considered therefore are:
Leafhoppers and treehoppers (four families)
Order Homoptera Jumping plant lice (Chermidae)
Plant lice or aphids (Aphididae)
Scale insects (Coccidae)