Thoracic Appendages 431 Legs

In the vast majority of insects each thoracic segment bears a pair of legs. In the cases where legs are absent, for example, in all dipteran, and many coleopteran and hymenopteran larvae, the condition is secondary. Typically, the legs are concerned with walking and running, but they may be specialized for a range of other physical functions, some of which are described below. In addition, for many insects they are important organs of taste

FIGURE 3.21. (A) Hypothetical ground plan of leg podites in ancestral insect; and (B) typical leg of a modern insect. [A, after J. Kukalova-Peck, 1987, New Carboniferous Diplura, Monura, and Thysanura, the hexapod ground plan, and the role of thoracic side lobes in the origin of wings (Insecta), Can. J. Zool. 65:2327-2345. By permission of the National Research Council of Canada and the author. B, from R. E. Snodgrass, Principles of Insect Morphology. Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]

FIGURE 3.21. (A) Hypothetical ground plan of leg podites in ancestral insect; and (B) typical leg of a modern insect. [A, after J. Kukalova-Peck, 1987, New Carboniferous Diplura, Monura, and Thysanura, the hexapod ground plan, and the role of thoracic side lobes in the origin of wings (Insecta), Can. J. Zool. 65:2327-2345. By permission of the National Research Council of Canada and the author. B, from R. E. Snodgrass, Principles of Insect Morphology. Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]

(see Chapter 12, Section 4.1). As noted earlier, Kukalova-Peck (1987) suggested that the ancestral limb included 11 podites, as well as exites and endites (Figure 3.21A). Because of fusion of podites with the pleuron or with adjacent podites the full complement of podites in the leg is never seen, though in many fossils and a few extant Ephemeroptera and Odonata as many as eight podites can be identified.

Typical Walking Leg. The leg consists of six podites, the coxa, trochanter, femur, tibia, tarsus, and pretarsus (Figure 3.2lB). Between adjacent parts are a narrow, annulated membrane, the corium, and usually a mono- or dicondylic articulation.

The coxa is a short, thick segment strengthened at its proximal end by an internal ridge, the basicosta (Figure 3.22). The coxa usually has a dicondylic articulation with the pleuron. In some orders the basicostal sulcus is U- or V-shaped over the posterior half of the coxa (Figure 3.22). The sclerite thus demarcated becomes thickened and is known as the meron. The trochanter is a small segment. It always has a dicondylic articulation with the coxa but is usually firmly fixed to the femur, which is generally the largest leg segment. Following the slender tibia is the tarsus, a segment that is usually subdivided into between two and five tarsomeres and a pretarsus. The pretarsus, in most insects, takes the form of a pair of tarsal claws and a median lobe, the arolium (Figure 3.23).

-pleural articular socke*

basicostal sulcus

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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