HYMENOPTERA. 
2 I 
lias been clearly shown to exist amongst the Cynipidce. It is a remarkable fact, 
too, that the galls produced by a parthenogenetic female are different in form from 
those produced by a female originating from the normal sexual process. The 
insects produced by these different galls were for many years looked upon as 
distinct species. It is, of course, on the cell-tissues of the gall that the larvae of 
the Cynipidce feed and thrive; they themselves, however, in their turn being 
subject to the attacks of numerous hymenopterous parasites of various kinds. 
Of the typical genus, we may take the common oak-gall wasp {Cynips folii) 
as a familiar example. It is a glistening black insect, which forms an oak-gall on 
the under side of oak-leaves. A parasite {Torymus 
regius) lays its own egg upon the larva of the 
Cynips lying within the gall, when the latter is 
about half grown. Another species ( Cy nips gemmce ) 
is produced from conical scale-covered galls, sprout¬ 
ing from the young shoots of the oak, in the interior 
of which the grubs feed. The illustration on p. 20 
shows the gall produced by insects of this species. 
To the same family belongs the sponge gall-wasp 
(Teras terminalis), which emerges from many- 
chambered spongy galls. • In spring these galls are 
light coloured; but later on, when the insect has 
made its escape, become brown. The female insects 
may be either winged or wingless, whereas the males 
are always provided with these appendages. Up¬ 
wards of forty parasites have been reared from the 
galls of this species. Yet another familiar type is 
the bramble gall-wasp ( Diastrophus rubi), which in 
spring produces hard and often twisted swellings on 
bramble-stems, from which in due course emerge 
the perfect insects. In the same illustration is 
shown the oak - root gall - wasp ( Bioriza aptera). 
In this form the female is wingless, but the male is 
unknown. The galls are formed on the rootlets of 
the oak-trees beneath the surface of the ground. 
In the common rose-gall wasp ( Rhodites rosce), which produces the so-called 
bedeguan gall on roses, the larvae are full-fed in autumn, although the perfect insect 
does not appear till the following spring. Their beautiful, mossy, pink-tinted galls 
furnish a home for many other insects, such as various species of Synergus, but 
especially parasites belonging to the families Pteromalidce and Braconidce. 
Synergus facialis, of which a figure is given in the lower illustration on p. 20, is 
parasitic on the gall-wasps. So too is Figites scutellaris, shown in Fig. 6 of the 
same illustration. These are gall-wasps, so far as structure is concerned; but as 
regards their habits they are in no way different from ichneumons, living in the 
larval state in the bodies of various insects. Figites scutellaris, as well as most 
other members of the group, arc parasitic on the larvae of the flies; while Ibalia 
cidtellator is parasitic in the larvae of the giant saw-flies. 
ROSE GALL-WASP AND ITS GALL. 
