70 
ON THE LARVA AND PUPA OP A PARASITIC PHORID 
ELY —HYPOCERA IN CRASS AT A MG. 
By HUBERT M. MORRIS, M.Sc., F.E.S. 
(Entomological Dept., Institute of Plant Pathology, Rothamsted 
Experimental Station, Harpenden.) 
(Plate III and 4 Text-figures.) 
CONTENTS. 
PAGE 
1. The Larva ..... 70 
2. The Puparium .... 73 
3. The Pupa . ... 73 
4. Emergence of Adult from Puparium 73 
PAGE 
5. Comparison with Larvae of other 
Phoridae ..... 74 
6. References to Literature ... 74 
7. Description of Plate ... 74 
On Jan. 27th, 1920, among a number of nearly fully grown larvae of Bibio 
marci which had been kept in the laboratory about two weeks, a few individuals 
were observed to be unhealthy or dead. These latter were found to contain 
parasitic Dipterous larvae, which eventually proved to be those of Hypocera 
incrassata Mg. Certain of these larvae were observed to be leaving the bodies 
of other larvae of Bibio marci at the same time. 
The larvae of Hypocera incrassata pupated in the soil immediately after 
leaving their hosts, and only a single parasite was observed in each of the latter. 
The pupae were kept in soil in the laboratory, and the adults emerged 
between June 24th and July 1st. 
The larva and pupa of Hypocera incrassata appear to be undescribed. It is 
noteworthy that H. vitripennis is recorded as having been reared from humble- 
bees’ and wasps’ nests (4), and H. vectabilis from dried specimens of Coleoptera (l). 
The present species is of additional interest as being the first definite 
record of an insect parasitic on Bibionid larvae. 
I am indebted to Dr D. Keilin for the identification of the adult flies s and 
for the information regarding previous records of the rearing of species of 
Hypocera. I am also much indebted to Dr A. D. Imms for advice during the 
preparation of this paper. 
1. THE LARVA. 
The larvae were not observed until they were leaving, or about to leave, 
the body of the host, and were then fully grown. At this stage they are about 
8-0 mm. to 8-5 mm. in length and about 2-0 mm. in breath, and are of a yel¬ 
lowish-white colour. 
