36 Dr. D. Keilin on the Larve ce. of 
to Meigen (1818, t. i. p. 230), who found a young undeveloped 
male of this fly in Polyporus versicolor. 
Zetterstedt (1851, t. x. p. 4071) quotes Behrens, who 
bred this insect from a fungus which he found on Juglans 
regia. 
According to Winnertz (1863, p. 669), the larve of 
D. fasciata live in different Polyporus and especially im 
P. versicolor and ferrugineus; he quotes also Kalteubach 
who bred )). macroptera, Winuertz, from Polyporus ignarius. 
Schiner (1864, 1. p. 428) reared D. fasciata from various 
Polypori. 
Frauenfeld (1866, p. 200) found the larve of this specics 
in Polyporus squamosus ; he also gave the first description of 
the larval and pupal stages of this fly. Unfortunately, his 
very short description does not contain any figure, and may 
be applied to many other dipterous larve. The only 
characters of his description worth mentioning are the 
following: (1) the imtersegmental spaces are deeply cou- 
stricted, (2) the first segment of the thorax is large, and 
(3) the posterior end of the body bears two protuberances 
ended by a sharp spine. 
We have, finally, to mention that the collection in the 
Entomological Museum of Cambridge contains the pup 
and adults of Vitomyia fasciata, Mg., reared by Fryer (1910) 
from Polystictus versicolor collected at Chatteris (Cambs) 
and by H. Scott (1910) from the same fungus collected from 
beech-stumps at Henley-on-Thames. 
I received the larvee and pupe of Ditomyia fasciata, which 
will be described here, from Mr. F. W. Edwards, who found 
them in a fungus, which the beheves to be Polystictus versi- 
color, growing on old Beeeh-sinaps near Cambridge and at 
Baldock, Herts. 
Later on, 1 collected myself a few of these larve in a 
piece of wood covered and penetrated by the mycelium of a 
fungus. ° 
According to Edwards, in nature the larve usually live 
upon the old fungi, but in his breeding-jars he observed 
them attacking the fresh fungi also. 
‘Che larvee are opaque white in colour and have very little 
power of movement. Pupation takes place within tlie 
fungus without the formation of any cocoon ; before the 
emergence of the adult the pupa bores its way to the surface 
and comes halfway out. 
‘The larva is 9°3 mm. long, with very deep intersegmental 
grooves (PI. IV. fig. 14). 
