I 1 6 TEANSACTIONS OF THE ILLINOIS 



Its larval skin now begins to contract in length and in a short time 

 splits open along the head and back, the pupal skin having been formed 

 in the mean time from the inner surface of the larval skin, by peeling off 

 as it were the inner portion of that skin. Casting off the old skin, the 

 semi-torpid and limbless pupa supports itself by the silken loop and little 

 booklets attached to the mat (pointing to the drawings). Marked 

 changes have been going on and are still going on in the body; the 

 muscles at some points are swelling and expanding, while at others they 

 are diminishing; some segments infolding and contracting, while others 

 are increasing their dimensions. The nervous system is also being 

 materially modified. In fact there is an almost total destruction of the 

 larval system of internal organs, and many of the external appendages 

 disappear. 



To supply the material for the new organs, the fatty matter stored 

 up by the larva is broken up into granules, which produce, by the multi- 

 plication of cells, the new tissues. 



It is upon this fatty matter internal parasites live, and while it does 

 not destroy the larva, yet prevents the development of the perfect insect. 



There is an almost complete tearing down of the old body and 

 building up of a new one; and thus is accomplished the seemingly im- 

 possible feat proposed by the Hibernian, of erecting on the site of the old 

 one, and of the same materials, a new house without removing the old one. 



How different in form now is our insect. Instead of a sixteen-footed, 

 wingless worm, we have a six-footed insect with broad, gaudy wings 

 (pointing to diagram); instead of a mouth with biting jaws, there is an 

 oral apparatus in the form of a long, slender, flexible tube, suited only 

 for sucking nourishment. 



What has wrought these wonderful changes? You will doubtless 

 answer, life. But what is life; and how has it performed this strange 

 feat of inimitable workmanship? Was it only a latent force that lay hid 

 in the food gathered from the external world? If so, then we may truly 

 say it was all done by the gardener's cabbage-leaf As well might you 

 say that cod-fish and potatoes wrote Hiawatha, and that pork and beans 

 were the authors of the Declaration of Independence. 



Let us now turn our attention to another insect, in which life, as 

 though desirous of showing its varied power over matter, exhibits still 

 more remarkable feats. In the cabbage-worm, as well as all metabolic 

 insects, the strangest part of their life-history consists in the changes from 

 one form and mode of life to another. In the case now to be adduced 

 we shall see not only more remarkable changes but new features. 



If we examine the abdomen of burrowing bees {AndrencB) during the 

 months of May and June we will probably find, projecting between two 

 contiguous segments, what appears to be the head of an insect. If we 

 can succeed in drawing the body from its concealed position, we shall 

 perceive a singular form, resembling this (calling attention to diagram), 

 which is entirely limbless and without any apparent appendages. This 

 flask-shaped creature, instead of being, as you might suppose, a grub or 

 larva, is in fact a full-grown, perfect insect, a mature female Sty lops, or 



