Psyllids Whiteflies Aphids and Scale Insects Suborder Sternorrhyncha

Tarsi 1- or 2-segmented (legs rarely lacking). Antennae long and threadlike (rarely absent). Mostly rather inactive insects.

Superfamily Psylloidea

PSYLLIDS Family Psyllidae See also PL 4

Identification: FW membranous or thickened. Wings usually held roojlike over body at rest. Tarsi 2-segmented. Antennae 10-segmented. Active jumping insects, 2-5 mm.

Most psyllids are free-living and feed on a variety of plants. A few are gall makers, generally forming galls on hackberry leaves. Nymphs are oval and flat and look very little like the adults; many produce a large amount of waxy filaments, making them look like little blobs of cotton. Some psyllids resemble tiny cicadas. A few species are pests of orchard trees or garden plants. One western species acts as vector of a plant disease known as "psyllid yellows."

Superfamily Aleyrodoidea

WHITE FLIES Family Aleyrodidae

Identification: Minute whitish insects, generally 2-3 mm. Body and wings covered with a white powder. HW nearly as large as FW. Wings held horizontal over body at rest. Tarsi 2-segmented. Antennae 7-segmented. Compound eyes somewhat elongate vertically and narrowed in middle.

Whiteflies are chiefly tropical, and our most common species are those attacking citrus or greenhouse plants. The 1st ins tar is an active insect; subsequent instars become covered with a blackish scalelike covering. Early instars are called larvae and the next to last instar, which is quiescent and does not feed, is called the pupa.

Aphids and Phylloxerans: Superfamily Aphidoidea

Wings, when present, membranous and not covered with a whitish powder. HW much smaller than FW. Tarsi 2-segmented. Body

APHID S 135

oval or pear-shaped, often with a pair of fingerlike cornicles near posterior end of abdomen. Many with a complex life cycle.

APHID S Family Aphididae See also Pl. 4

Identification: Soft-bodied, usually somewhat pear-shaped, 4-8 mm., nearly always with a pair of cornicles near posterior end of abdomen. FW of winged forms with Rs present and M branched. Wings at rest usually held vertical above body.

This is a large group, and its members are often found in considerable numbers on the stems, leaves, and flowers of various plants. Many are serious pests of cultivated plants; their feeding causes a curling or wilting of the plant, and-some aphids serve as vectors of plant diseases.

Most aphids have a complex life cycle, involving bisexual and parthenogenetic (?) generations, winged and wingless individuals or generations, and often a regular alternation of food plants. Aphids generally overwinter as eggs, which hatch in the spring into wingless females that reproduce parthenogenetically (without fertilization) and give birth to young (rather than eggs). Two or more generations of such females may be produced; a generation of winged females eventually appears that usually migrate to a different food plant. These winged females also reproduce parthenogenetically, giving birth to young. Late in the season winged forms return to the original food plant, and

a generation of males and females appears; these mate, and the females lay the eggs that overwinter.

Aphids discharge from the anus a clear watery liquid, called honey dew, to which ants and other insects are attracted. Some ants live closely associated with aphids. They gather aphid eggs and keep them over winter in their nest and transport the aphids to a food plant in spring, tending them during the season and transferring them from one food plant to another. The ants feed on honey dew produced by the aphids.

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