98 THB bbe-kebper's guide ; 



variation. There may be a score of them ; there may be 

 thousands. 



THE LARVA OF INSECTS. 



From the egg' comes the larva, also called grub, maggot, 

 caterpillar, and very erroneously worm. These are worm- 

 shaped (Fig. 39), usually have strong jaws, simple eyes, and 

 the body plainly marked into ring divisions. In some insects 

 there are fourteen of these rings or segments, or ten besides the 

 head and three rings of the thorax. In bees, and nearly all 

 other insects (Fig. 39,7^), there is one less abdominal ring. 

 Often, as in case of some grubs, larval bees, and maggots, 

 there are no legs. In most grubs there are six legs, two to 

 each of the three rings succeeding the head. Besides these, 

 caterpillars have usually ten prop-legs farther back on the 

 body, though a few — the loopers or measuring caterpillars — 

 have only four or six, while the larvae of the saw-flies have 

 from twelve to sixteen of the false or prop-legs. The alimen- 

 tary canal of larval insects is usually short, direct, and quite 

 simple, while the sex-organs are slightly if at all developed. 

 The larvK of insects are voracious eaters — indeed, their only 

 work seems to be to eat and grow fat. This rapid growth is 

 well shown in the larva of the bee, which increases during its 

 brief period from egg to full-grown larva — less than five days — 

 from 1200 to 1500 times its weight. As the entire growth 

 occurs at this stage, their gormandizing habits are the more 

 excusable. I have often been astonished at the amount of food 

 that the insects in my breeding cases would consume. The 

 skin or crust of insects is unyielding, hence growth requires 

 that it shall be cast. This shedding of the skin is called 

 moulting. It is a strange fact, already mentioned, that the 

 treacheae and a part of the alimentary canal are cast off with 

 the skin. Most insects moult from four to six times. That 

 bees moult was even known to Swammerdam. Vogel speaks 

 of the thickening of the cells because of these cast-skins. Dr. 

 Packard observed many years since, that in the thin-skinned 

 larvae, such as those of bees, wasps, and gall-flies, the moults 

 are not apparent ; as these larvse increase in size, they out- 

 grow the old skin which comes off in shreds. The length of 



