Hatching

To escape from the egg, a larva must break through the various membranes that surround it. These include the chorion, vitelline membrane, and, in eggs of some species, serosal cuticle. Further, in many exopterygotes and some endopterygotes a newly hatched larva is surrounded by embryonic cuticle that also must be shed before the insect is truly free.

The general mechanism of hatching is as follows. An insect first swallows amniotic fluid,* followed usually by air, or water, which diffuses into the egg. The abdomen is then contracted to force hemolymph into the head and thorax, which enlarge and cause the egg membranes to rupture. To facilitate rupture the chorion may have predetermined lines of weakness that run longitudinally or transversely, the latter separating an anterior egg cap from the more posterior portion of the egg. In many species, egg bursters, in the form of hard cuticular spines or plates, or thin eversible bladders, may develop on the head, thorax, or abdomen. In Acrididae and those Hemiptera in which pleuropodia develop, it is believed that these glands secrete chitinase that dissolves the serosal cuticle as an aid to hatching. Larvae of Lepidoptera simply eat their way out of the egg.

Where an embryonic cuticle is present, this may be shed concurrently with the other enclosing membranes, or may ensheath a larva until it has completely escaped from the egg, as in Odonata, Orthoptera, and some Hemiptera. In these insects the embryonic cuticle underwent apolysis some time prior to hatching, and the first-instar larval cuticle is already formed beneath. Thus, the insect hatches as a pharate first-instar larva. In Orthoptera and endophytic Odonata, the embryonic cuticle presumably protects a larva until it reaches the surface of the substrate in which the egg was laid. In other species, however, its function is unclear. It is shed a few minutes after a larva has reached the surface, a process called the intermediate molt.

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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