HVMENOI'TERA. 209 



other parts of trees and plants, in each of which it first deposits an 

 egg, and then a foaming' liquid, the use of which, it is presumed, is to 

 prevent the aperture from closing. The wounds made in this way 

 become more and more convex by the increasing size of the egg. 

 Sometimes these excrescences assume the form of a gall-nut, either 

 ligenous or soft and pulpy, or resemble a little fruit, according to the 

 nature of the parts of the plant that arc affected by them. These 

 tumours then form the domicil of the larvae which inhabit them 

 either solitarily or in society. There they undergo their metamor- 

 phosis, and issvie fi'om them through a circular opening made in their 

 parietes by the teeth of the Insect. Generally speaking, however, 

 these larvaj live exposed on the leaves of the trees and plants on 

 which they feed. In the general form of the body, its colours, the 

 exterior disposition of its dermis, and in the great number of feet, 

 these larvcie closely resemble caterpillars, and have been called false, 

 pseudo-caterpillars : but they are distinguished from the latter by 

 having from eighteen to twenty-two feet, the number of these organs 

 in the caterpillar being from ten to sixteen. Several of these pseudo- 

 caterpillars roll themselves up spirally ; in others the posterior por- 

 tion of the bod}^ is arched. In order to become nymphs, they spin a 

 cocoon, either in the earth, or on the plants where they have lived. 

 There they pass several consecutive months, or even the whole Avin- 

 ter, in their first state, and only pass into that of a nymph a few days 

 previous to the one in which they appear as perfect Insects or Saw- 

 flies. 



M. Dutrochet, corresponding member of the Academic des Sci- 

 ences, has published some observations on the alimentary canal of 

 these Insects in the Journal Physique. 



In some, where the antennae consist of but nine joints, and where 

 the internal extremity of the two anterior tibiae is furnished Avith 

 two straight and divergent spines, the ovipositor does not project 

 posteriorly. 



Here the labrum is always apparent, and the middle of the inner 

 side of the four posterior tibipe is destitute of spines, or presents but 

 one. The larvse or pseudo-caterpillars have from twelve to sixteen 

 membranous feet. 



The antennae, always short, sometimes terminate either in a thick 

 inflation in the form of a reversed cone rounded at the extremity, or 

 of a button, or in a large joint forming an elongated, prismatic or 

 cylindrical club forked in some males ; the number of the preceding 

 joints is five at most. 



Those species, in which these organs, similar in both sexes, are 

 terminated by a globuhform inflation, or by one resembling a re- 

 versed cone rounded at the extremity *, and preceded by from four 

 to five joints, and where the two nervures of the superior Avings form- 

 ing the rib, as far as the callous point, are contiguous, or closely 



* This inflation is formed by the fifth or sixth joint, but which, in several, pre- 

 sents vestiges of two or three annular divisions. 



