General Structure

Primitively the head is oriented so that the mouthparts lie ventrally (the hypognathous condition) (Figure 3.3B). In some insects, especially those that pursue their prey or use their mouthparts in burrowing, the head is prognathous in which the mouthparts are directed anteriorly (Figure 3.4A). In many Hemipterathe suctorial mouthparts are posteroventral in position (Figure 3.4B), a condition described as opisthognathous (opisthorhynchous).

The head takes the form of a heavily sclerotized capsule, and only the presence of the antennae and mouthparts provides any external indication of its segmental construction. In most adult insects and juvenile exopterygotes a pair of compound eyes is situated dorsolater-ally on the cranium, with three ocelli between them on the anterior face (Figure 3.3A). The two posterior ocelli are somewhat lateral in position; the third ocellus is anterior and median. The antennae vary in location from a point close to the mandibles to a more median position between the compound eyes. On the posterior surface of the head capsule is an aperture, the occipital foramen, which leads into the neck. Of the mouthparts, the labrum hangs down from the ventral edge of the clypeus, the labium lies below the occipital foramen, and the

* Perhaps the most interesting conclusion was drawn by Snodgrass (1960, p. 51) who stated "it would be too bad if the question of head segmentation ever should be finally settled; it has been for so long such fertile ground for theorizing that arthropodists would miss it as a field for mental exercise"!

FIGURE 3.3. Structure of the typical pterygotan head. (A) Anterior; (B) lateral; (C) posterior; and (D) ventral (appendages removed). [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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