IIYMENOPTERA. 
] 9 
purposes they may, however, he divided into Parasitica, or those in which the 
females are furnished with an ovipositor, and Aculeata, or those in which the 
ovipositor has become modified into a retractile sting. 
G all- W asps,— Family C YNIPIDjE. 
Of the former, or parasitic section of the suborder, our first representatives are 
the gall-wasps ( Cynipidce ), all of which are small and inconspicuous insects, vary¬ 
ing in colour from black to brown and brownish red. The wings are furnished 
with few nervures, and the dark stigma on the anterior margin is absent; while 
in some species the females have the wings either rudimentary or altogether want¬ 
ing. Of the galls so common on the foliage of trees and other plants, some are 
produced by beetles, aphides, flies (gall-midges), and others by the members of 
the present family and some of the TenthredinicLce. In the gall - wasps each 
species selects some special portion of the plant for its attack, which it pierces with 
green saw-fly, Tenthredo scalaris (nat. size). 
its ovipositor, and lays an egg in the wound. As to what exactly gives rise to the 
resultant gall, which follows sooner or later upon the wounded plant, is not known 
with any certainty. It has hitherto been supposed that the fly injects an irritat¬ 
ing fluid into the wound, but recent researches tend to show that this serves rather 
as an adhesive security to retain the egg on the selected spot. It is probable that 
the different stimulative irritants offered, first by the inflicted wound, next by the 
presence of the eggs, and thirdly by the movements of the larva after it is hatched, 
together with the action of a fluid exuded by the grub itself, all tend to produce 
the strange modifications of cell structure which manifest themselves in the forms 
of the various kinds of galls. The larvse of the Cynipidce almost entirely feed 
internally upon galls produced on oak-leaves and the oak-blossoms. These galls 
are entirely closed, and the grub dwells within a hard cell, called the larval 
chamber. In some cases there may be several such chambers, as, for instance, in 
the Bedeguar-gall on the wild rose-tree formed by Rhodites rosea. A\ e have said 
that each species confines itself to one portion of the plant, and the form of the 
gall is the same; but an exception is furnished by the galls of Spathegaster bac- 
carum, which occur upon the leaves as well as on the flower-tassels of the oak. 
