The Head

The head, being the anterior tagma, bears the major sense organs and the mouthparts. Considerable controversy still surrounds the problem of segmentation of the insect head, especially concerning the number and nature of segments anterior to the mouth.* At various times it has been argued that there are from three to seven segments in the insect head, though it is now widely agreed that there are six. It is not feasible to discuss here the many theories concerning the segmental composition of the insect head, but the main points of contention should be noted. These are: (1) whether arthropods possess an acron (which is non-segmental and homologous with the annelid prostomium); (2) whether a preantennal segment occurs between the acron and the antennal segment and what appendages are associated with such a segment; and (3) whether the antennae are segmental appendages or merely outgrowths of the acron [see Rempel (1975), Bitsch (1994), Kukalova-Peck (1992), and Scholtz (1998) for reviews of the subject]. The embryological studies of Rempel and Church (1971) have demonstrated convincingly that an acron is present. However, it is never seen in fossil insects or other arthropods (Kukalova-Peck, 1992) because it moved dorsally to merge imperceptibly into the region between the compound eyes (Kukalova-Peck, 1998).

Both embryology and paleontology have confirmed that there are three preoral and three postoral segments The first preoral segment is preantennal; it is called the protocerebral or clypeolabral segment. The segment itself has disappeared but its appendages remain as the clypeolabrum. The second preoral (antennal/deutocerebral) segment bears the antennae, which are therefore true segmental appendages. The third preoral (intercalary/tritocerebral) segment appears briefly during embryogenesis, then is lost. Its appendages, however, remain as part of the hypopharynx (Kukalova-Peck, 1992). Head segments 4-6 are postoral and named the mandibular, maxillary, and labial, respectively. Their appendages form the mouthparts from which their names are derived. In addition, the sternum of the mandibular segment becomes part of the hypopharynx.

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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