Movement on or Through a Substrate 311 Walking

Insects can walk at almost imperceptibly slow speed (watch a mantis stalking its prey) or run at seemingly very high rates (try to catch a cockroach). The latter is, however, a wrong impression created by the smallness of the organism, the rate at which its legs move, and the rate at which it can change direction. Ants scurrying about on a hot summer day are traveling only about 1.5 km/hr, and the elusive cockroach has a top speed of just under 5 km/hr (Hughes and Mill, 1974).

Nevertheless, an insect leg is structurally well adapted for locomotion. Like the limbs of other actively moving animals, it tapers toward the distal end, which is light and easily lifted. Its tarsal segments are equipped with claws or pulvilli that provide the necessary friction between the limb and the substrate. A leg comprises four main segments (Chapter 3, Section 4.3.1), which articulate with each other and with the body. The coxa articulates proximally with the thorax, usually by means of a dicondylic joint and distally, with the fused trochanter and femur, also via a dicondylic joint. Dicondylic joints permit movement in a single plane. However, the two joints are set at right angles to each other and, therefore, the tip of a leg can move in three dimensions.

The muscles that move a leg are both extrinsic (having one end inserted on the wall of the thorax) and intrinsic (having both ends inserted within the leg) (Figure 14.5). The majority of extrinsic muscles move the coxa, rarely the fused trochantofemoral segment, whereas the paired intrinsic muscles move leg segments in relation to each other. Some of the extrinsic muscles have a dual function, serving to bring about both leg and wing movements. Typically, the leg muscles include (1) the coxal promotor and its antagonist, the coxal remotor, which run from the tergum to the anterior and posterior edges, respectively,

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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