General Body Plan

Like other arthropods insects are segmented animals whose bodies are covered with cuticle. Over most regions of the body the outer layer of the cuticle becomes hardened (tanned) and forms the exocuticle (see Chapter 11, Section 3.3). These regions are separated by areas (joints) in which the exocuticular layer is missing, and the cuticle therefore remains membranous, flexible, and often folded. The presence of these cuticular membranes facilitates movement between adjacent hard parts (sclerites). The degree of movement at a joint depends on the extent of the cuticular membrane. In the case of intersegmental membranes there is complete separation of adjacent sclerites, and therefore movement is unrestricted. Usually, however, especially at appendage joints, movement is restricted by the development of one or two contiguous points between adjacent sclerites; that is, specific articulations are produced. A monocondylic joint has only one articulatory surface, and at this joint movement may be partially rotary (e.g., the articulation of the antennae with the head). In dicondylic joints (e.g., most leg joints) there are two articulations, and the joint operates like a hinge. The articulations may be either intrinsic, where the contiguous points lie within the membrane (Figure 3.1A), or extrinsic, in which case the articulating surfaces lie outside the skeletal parts (Figure 3.lB).

FIGURE 3.1. Articulations. (A) Intrinsic (leg joint); and (B) extrinsic (articulation of mandible with cranium). [From R. E. Snodgrass, Principles of Insect Morphology. Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]

In many larval insects (as in annelids) the entire cuticle is thin and flexible, and segments are separated by invaginations of the integument (intersegmental folds) to which longitudinal muscles are attached (Figure 3.2A). Animals possessing this arrangement (known as primary segmentation) have almost unlimited freedom of body movement. In the majority of insects, however, there is heavy sclerotization of the cuticle to form a series of dorsal and ventral plates, the terga and sterna, respectively. As shown in Figure 3.2B,

FIGURE 3.2. Types of body segmentation. (A) Primary; and (B) secondary. [From R. E. Snodgrass, Principles of Insect Morphology. Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]
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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