486 THE POPULAR SCIENCE MONTHLY, 



on without obstruction of any kind. According to A. Schenck, the 

 gall-nuts of the rose are adapted to the shelter and support of the larva) 

 of more than two hundred species of flies, and those of the oak are also 

 the home of numerous varieties. Malpigbi, who died near the end of 

 the seventeenth century, remarked that there was no part of the plant 

 on which galls did not arise. The roots, runners, stalks, leaf-stems, 

 leaves, buds, flower-stems, flowers, and fruit, all are made to serve as 

 the nest or place of transformation for the young of one or more species 

 of insect ; but only the aphis lives upon them permanently. 



Another very frequently observed means of securing young insect 

 broods is by envelopes formed, sometimes with great apparent skill, by 

 rollings or foldings of the leaf. Some weevils have the art of cutting 

 out patterns of leaves, and, without wholly severing their attachment, 

 rolling them up into a scroll, within which they deposit their eggs ; 

 and they do the whole with such mathematical accuracy that their con- 

 structions have been made the subjects of formal monographs, like 

 those of Drs. Heis and Debey on the funnel-rollers. Specimens of 

 these scrolls are familiar enough, as they have been observed on the 

 hazel, beech, hornbeam, alder, birch, aspen, and vine, where the opera- 

 tions of the insects are in some seasons attended with injury to the 

 crop. The caterpillars of many butterflies and moths are also shel- 

 tered in the same manner ; while other caterpillars associate them- 

 selves together and spin webs for their nests, in the air between the 

 leaves and twigs of trees. Nests of this kind are frequently found on 

 fruit-trees and shrubbery, and afford a very good degree of protection 

 to their inhabitants against late frosts, storms, birds, and parasites. 

 The nest of the procession-spinner serves, curiously, only as a resting- 

 place for the insect in the larval state, though it finally becomes the 

 common home of the pupae. The caterpillars, to satisfy their hunger, 

 are accustomed to leave the nest in a kind of orderly procession, climb- 

 ing up the stem of the tree to wander all over the crown of the foliage, 

 and, after they have done their work, to return again in procession to 

 their nest. They are avoided by man on account of the irritation pro- 

 duced by the sting of their hairs, and are for the same reason safe 

 against all birds but the cuckoo. A carnivorous beetle, the Calosoma 

 sycophanta, also despises their fortress and their weapons, and breaks 

 voraciously into their communities, like a wolf into a sheep-fold. We 

 must remember here, the consummate architectural skill with which 

 honey-bees build up their combs of waxen cells closely joined one to 

 another. Their whole manner of life and their professional division 

 of labor, in which they remind us of civilized human life, provoke the 

 query, Whence the mechanical and technical skill and the intelligence 

 of these little creatures ? 



A considerable number of our insects are burrowers, and during 

 the period of their larval development excavate, under the epidermis 

 of the leaves and other green parts of plants, passages, small at first, 



