37 [ 457 J 



The origin and natnre of these globules, and the part which they ful- 

 fill in the economy of the insect, are matters of conjecture. We do not 

 know, with certainty, whether they originate from the insect itself, or 

 from the inner surface of the gall. The most plausible supposition is 

 that they are secretions from the bodies of the insects, probably from 

 their anal extremit\^, and that they bear some analogy to the drops of 

 sacharine fluid secreted from the honey-tubes of the true Aphides. 



The mouths of these galls do not close so closely, at least in the latter 

 part of the season, as to exclude a variety of i^redaceous and parasitic 

 enemies, by which their numbers are greatly reduced. If we examine 

 them in the latter part of July and subsequently, we often find but few 

 lice remaining, and in their place some one or other of their natural 

 enemies. I have found within them minute, black, four- winged flies of 

 the Chalcis family. Also, the larvae of some small, two-winged Syrphus 

 fly, known by their oblong, pear-shaped form, tapering to a point ante- 

 riorly, and their snake-like manners. These larva? appear to be blind, 

 and they discover their prey by moving their pointed anterior extremity 

 from side to side. I have also seen a considerable number of green- 

 ish-yellow, semi-pellucid grubs, of a short ovoid form, abruptly pointed 

 posteriorly, apparently too large to be the larvie of the Chalcides, and 

 being more x)iobably the larvse of some species of Ichneumon fly. 



But their most common destroyer is a small Hemijjterous insect be- 

 longing to the genus Anthocoris, and closely allied to, if not identical 

 with, the Anthocoris musculosus of Say. From one to half a dozen of 

 these predaceous insects are often found in one of these galls in the lat- 

 ter part of the season. The fully matured insects are one-eighth of an 

 inch long, and are bf a glossy-black color, with brown and white wings. 

 The young larvse are scarlet-red. 



PRACTICAL REMARKS ON THIS AND OTHER SPECIES OF APHIDES. 



The extensive family of Aphides, viewed with respect to then* modes 

 of life, may be divided into four sections. 



First. The leaf-lice or Aphides proper, distinguished by their long, 

 tapering seven-jointed antennee, and the honey-tubes on their abdomens 

 These live on the leaves both of trees and herbaceous plants, or on the 

 tender growth of the current year. They are diffused upon almost all 

 kinds of vegetation, and those subsisting upon difierent kinds of plants 

 are often so much alike in their organic characters as to render it doubt- 

 ful whether they are different species, or mere plant- varieties of the 

 same. The Aphides are very tender insects and are often extensively 

 destroyed by sudden changes of the weather. The most troublesome 

 variety is that which infests hot-houses, where they luxuriate in the ar- 

 tificial protection and warmth provided for the j)lants. The common 



