4AQ MODERN CLASSIFICATION OF INSECTS. 
gall-like protuberances on the leaves of trees. The group, as pro- 
posed by Leach, corresponds with Latreille’s 3d section of Aphis, and 
comprises the Aphides Gallarum Ulmi, Tremulz, Xylosthei, and Gal- 
larum Abietis, all figured by De Geer. The last-named species re- 
cedes much from the rest of the family, and approaches nearer to the 
Coccidz, especially in the nearly globular form of the swollen females, 
which have very short legs, antennze, and proboscis, but the seta of the 
latter organ are capable of being greatly exserted. 
The species of this family are greatly subject to the attacks of other 
insects; the larvee of the Hemerobiide, the Coccinelle in the larva 
and imago states, and the larvee of various species of Syrphide feed 
upon them, and destroy vast numbers, whilst they are parasitically at- 
tacked by numerous minute Hymenoptera, belonging to the families 
Chalcidide, Proctotrupidz, Cynipidee, and Ichneumonide ; indeed, one 
of the genera of the Adscitous Ichneumons is named Aphidius. 
When an Aphis has received an egg of one of these parasites, it quits 
its companions, and fastens itself by its ungues to the under side of a 
leaf, where it swells nearly into a globular form, its skin stretched 
out and dried up, and in a short time the perfect parasite escapes by 
a circular hole, the mouth of which sometimes remains like a trap 
door. Some of the fossorial Hymenoptera also provision their nests 
with Aphides (see anéé, p. 195.). 
The species require a careful monograph, although descriptions of 
detached species have been given by Curtis, Walker, Haliday, Blan- 
chard, L. Dufour, Van Heyden, Morrem, Burmeister, and other recent 
authors. 

The family ALEYRODID# consists of the minute species of the genus 
Aleyrodes (jig. 118. 1. A. Chelidonii, magn. ; 2. ditto in repose, three 
times nat. size), distinguished from the Aphide by the broad, fari- 
nose, and nearly equal-sized wings, and still more by the transform- 
ations; and from the Coccide by both sexes being furnished with 
four wings in the perfect state. The head is small (jig. 118. 3.), with 
the eyes bipartite (fig. 118, 4.), and not emarginate, as stated by 
Latreille (A. An. tom. v. p. 228.) ; the antenne are short and 6-jointed ; 
the promuscis is short, and apparently only 2-jointed, the basal joint 
longest, and the last short and conical, as is also the labrum, from the 
extremity of which I extracted two curved sete in one specimen 
(fig. 118. 4.); the collar is short and transverse ; the abdomen neither 
