245 
trom a single host, which bore 13 eggs, four parasites. In addition 
to these Taehinas also 6 Ichneumon tlies vvere bred from cater- 
piilars with Tachina-eggs. In all the 150 caterpillars bore 767 
eggs, and the number of bred dies was 144, so that only about 
a fourth of the parasites succeeded in aecomplishing their develop- 
ment, The size of the dies was of course very variable, dift'ering 
between 5 mm. and lo mm.; in the cases where several dies 
emerged from the same host, their size was not equally reduced, 
one or two of thern not differing in size from that of dies which 
had developed solitary, the remainder being undersized. Allmost- 
all of the maggots pupated within the skin of the dead hosts. 
Tachina impotens Rond. 
Ihe larva is parasitic in the caterpillars of Orgyia antiqva L., 
which were found on a thorn-hedge in the neighbourhood of Copen- 
hagen. The eggs were deposited only on the fullgrown caterpillars 
and with few exceptions on the underside of the bodv, in the 
furrows between the thoracic segments or between the head and 
the drst segment. The dy was not common, and the caterpillars 
were nearl}’ all provided with only a single egg each — one only 
being found with two. Consequent to the maturity of the cater¬ 
pillars a great number of them pupated before the parasite had 
penetrated into their body and thus escaped being killed by the 
maggots; owing to this faet many of them, into which the Tachina 
maggots had penetrated, pupated, before they were killed. Of 34 
caterpillars 21 pupated before the Tachina-eggs were mature, and 
13 after the penetration; of the lastnamed 9 pupated before they 
were killed and only 4 were killed by the parasites before the 
pupation. The fullgrown Tachina-maggot leaves the remains before 
pupating and pupates in the hosts cocoon. The infested caterpillars 
were collected in the months of August—September, and all the 
dies emerged in October. 
