The Hemipteroid Orders

FIGURE 8.5. Psylloidea. The apple sucker, Psylla mali

(Psyllidae). [From A. D. Imms, 1957, A General Textbook ^^—^^rrciil^

of Entomology, 9th ed. (revised by O. W. Richards and R. G. Tp I

Suborder Sternorrhyncha

Like Auchenorrhyncha, Sternorrhyncha have an opisthognathous head without a gula, a small pronotum, and fore wings (when present) with a uniform texture and held rooflike over the body at rest. Derived features of recent sternorrhynchans include the position of the base of the proboscis (between or posterior to the fore coxae), two-segmented tarsi, no mesothoracic trochantin, a sawlike egg-burster, and various wing features, notably the absence of a vannus and vannal fold in the hind wing. Another feature that distinguishes them from auchenorrhynchans is their multisegmented, filiform antennae.

Superfamily Psylloidea

About 1400 of the 2200 species of Psylloidea are included in the family PSYLLIDAE. The jumping plant lice, as members of the family are commonly called, are small (2-5 mm long) and resemble miniature cicadas. They have strong hind legs, and wings are present in both sexes. The family contains many pest species, which may cause galls or a general stunting of host plants. The commonly held view that this stunting is caused by viruses for which psyllids serve as vectors is now believed to be wrong; it is the toxic saliva injected during feeding that causes the damage. Examples of pest species are Psylla pyricola and P. mali (Figure 8.5), two species introduced into North America from Europe, which feed on pear and apple, respectively. TRIOZIDAE (650 species worldwide) have similar habits to Psyllidae, in which family they are often included.

Superfamily Aleurodoidea

Included in the Aleurodoidea is a single family, ALEURODIDAE (ALEYRODIDAE), with approximately 1100 species, commonly known as whiteflies (Figure 8.6). They are small insects, usually 3 mm or less in length, generally covered with a whitish waxy secretion. They are commonly found on the underside of leaves. The group is mainly tropical or subtropical, though a few species are pests of greenhouse crops in temperate regions. The life cycle is complex, and parthenogenesis is commonly involved. Larvae are sedentary, and the final stage ("pupa") does not feed but undergoes a marked metamorphosis to the adult.

Superfamily Coccoidea

Some 20 families are included in the Coccoidea, a large, heterogeneous group of more than 7000 species. Despite this heterogeneity a unifying characteristic of the group is the more or less degenerate females. These are apterous, and may be scalelike, gall-like, or covered with a waxy or powdery coating. For this reason they are commonly known as scale

FIGURE 8.6. Aleurodoidea. The greenhouse whitefly, Trialeurodes vaporario-rum (Aleurodidae). [From L. Lloyd, 1922, The control of the greenhouse whitefly (Asterochiton vaporariorum) with notes on its biology, Ann. Appl. Biol. 9:1-32. By permission of the Association of Applied Biologists.]

insects or mealybugs. Adult males are either apterous or have fore wings only, and have nonfunctional mouthparts. Females are oviparous (in which case the eggs are usually retained within the scaly covering of a female), ovoviviparous, or viviparous. Parthenogenesis is common and hermaphroditism is known to occur in one genus. Many species have become cosmopolitan as a result of distribution by trade. Notes on some of the commoner families are given below. The DIASPIDIDAE (armored scales) form the largest family of coccoids with 2500 species worldwide. Females are covered with a hard, waxy layer that is separate from the body. Included in the family are many pests of trees and shrubs, for example, Lep-idosaphes ulmi, the oystershell scale (Figure 8.7A,B), and Quadraspidiotus perniciosus, the San Jose scale. Another large family is the COCCIDAE (soft scales, wax scales) (1200 species), the female members of which show a wide range of form. The family contains several pests that are now widespread through commerce; for example, Pulvinaria innu-merabilis, the cottony maple scale, introduced from Europe, is now found throughout North America feeding on forest, shade, and fruit trees. The KERRIIDAE (LACCIFERIDAE), a small (70 species), mainly tropical and subtropical group, have females that are extremely degenerate and live in a resinous cell. Laccifer lacca, the Indian lac insect, produces a secretion from which shellac is prepared. The PSEUDOCOCCIDAE (2000 species worldwide) are the common mealybugs, so-called because females are covered with a mealy or filamentous waxy secretion. Several species of Pseudococcus (Figure 8.7C) are major pests as they are vectors of disease-causing viruses. The ERIOCOCCIDAE (felt scales), a cosmopolitan group of some 500 species, were formerly included in the Pseudococcidae because of their close resemblance to mealybugs. The family contains a number of pest species, including some gall formers, as well as some potentially beneficial ones. Various Dactylopius species, for example, have been introduced into Australia in an attempt to control the prickly pear cactus (Opuntia) (see Chapter 24, Section 2.3). The MARGARODIDAE (ground pearls) (250 species) form a widely distributed family, included in which is Icerya purchasi, the cottony-cushion scale (Figure 8.7D), an Australian species that was transplanted through commerce to many regions of the world where it became an important pest of citrus fruit. In California this pest has been controlled successfully following the introduction of the predaceous beetle Rodolia cardinalis (see Chapter 24, Section 2.3).

Superfamily Aphidoidea

More than 4700 species of Aphidoidea have been described, including some of the world's most important insect pests. Some authors include all Aphidoidea in one family

FIGURE 8.7. Coccoidea. (A) The oystershell scale, Lepidosaphes ulmi (Diaspididae); (B) female L. ulmi; (C) female long-tailed mealybug, Pseudococcus longispinus (Pseudococcidae); and (D) male cottony-cushion scale, Icerya purchasi (Margarodidae). [A, B, from D. J. Borror, D. M. Delong, and C. A. Triplehorn, 1976, An Introduction to the Study of Insects, 4th ed. By permission of Holt, Rinehart and Winston, Inc. C, D, from P.-P. Grasse (ed.), 1951, Traité de Zoologie, Vol. X. By permission of Masson, Paris.]

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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