185 
pical parasite on Sialis eggs are easily attacked by spe- 
cimens captured distantly from water. 
On June 4th 1919 a number of eggs of Vite poly- 
chloros was found on Salix next to the bridge in Erme- 
lunden. Most of the eggs. were already bred and the 
larvas just elapsed sat close to the eggs. A few eggs 
were however not yet bred and turned out to be attacked 
by Trichogramma. The wasps were bred on June 10th 
1919. 
Centrobia Förster. 
1856 Centrobia Förster. Hym. Stud. II. 1956, p. 87. 
1918 ” Kryger. Entom. Meddel. XII, p. 287. 
In my formerly issued paper (1918) I am writing that 
genus Centrobia seems not to have been refound since 
Forster described it in 1851. 
There was however in the same year (1918) published 
an essay by Silvestri in Boll. del Lab. di Zool. gen. e 
agrar. d. R. Scuola sup. di Agricolt. in Portici vol. XII 
p. 245. This essay was however quite unknown to me 
when my paper was completed in printing towards the 
end of 1918; the volume of Boll. in question had owing 
to war not yet arrived here, which will account for my 
having not paid regard to the said essay. 
Silvestri reports that for some time he has been stud- 
ying the insects on oak (Quercus robur) and hazel (Cory- 
lus avellana) and that while devoting himself to these 
studies he succeeded in breeding some species of the 
genus Centrobia. One of these species he describes as 
Centrobia Walkeri Forster, but moreover he describes a 
variety of Walkeri, viz var. minor n. var. The drawings 
and the descriptions show that it is a good typical Cen- 
trobia which Silvestri has had before him. However I 
cannot agree to his opinion that the species should be 
Centrobia Walkeri; it must absolutely be a new species. 
is 
