187 
the median part of the thorax in extension equal to the 
breath of the scutellum (except the front part of scutellum 
which is chestnutbrown), the ascelli and the front part of 
the abdominal segments rustcoloured or ochreous; An- 
tennae reddish yellow, darker beneath; wings hyaline with 
brown veins, legs chestnut coloured with apex of femorae, 
base and apex of tibiae and the 2 first joints of tarsi rust- 
coloured, 3rd joint and pretarsus more or less dark. 
Length of the body (without ovipositor) 1 mm. 
Length of ovipositor, visible part 0,8 mm. 
Total length of ovipositor 1,56 mm. 
The male resembles the female also with regard to 
the colour. The other characteristics are seen on Silve- 
stris drawings. The aedeagus is produced 0,13 mm be- 
yond the apex of abdomen. 
Bred on May Ist to 23rd from oak twigs (Quercus 
robur) cut off the preceding autumn. The wasp may 
have been parasitic on eggs of some Hemiptera which 
has laid its eggs in the wood of the tree. 
2a. C. Silvestrii var. minor Silv. 
1918 Centrobia Walkeri var. minor Silvestri. Boll. Lab. Zool. gen. 
agrar. Sc. Agric. Portici XII, p. 250. 
Among the typical Silvestrü-specimen which Silvestri 
bred from oak twigs there were several specimens of a 
Centrobia agreeing with the main species except as to 
the size which was perceptibly smaller: 
Total length of the body 0.65 mm. 
Length of ovipositor, visible part 0.40 mm. 
Total length of ovipositor 0,78 mm. 
As Silvestri did not find sizes between this form and 
the main species he is of the opinion that it is a special 
variety. 
3. C. similis Silv. 
1918 Centrobia similis Silvestri. Boll. Lab. Zool. gen. agrar. Sc. 
Agric. Portici XII, p. 250. 
Female: Colour more or less .bright reddish yellow, 
anterior part of 3rd to 6th abdominal segments chestnut- 
brown, antennae and legs reddish yellow, wings hyaline 
with chestnut-brown veins. 
Length of the body 0,90 mm. 
