6 BULLETIN 1028, U. S. DEPARTMENT OF AGRICULTURE. 
OVIPOSITION. 
The act of oviposition takes about one second. The female may 
alight upon a gipsy-moth larva from flight or walk up to one. In 
either case the ovipositor is inserted and withdrawn very quickly and 
practically always an individual egg is deposited. Many larvae 
have been dissected after apparent oviposition had been observed 
and in no case has more than one egg been found from a single 
oviposition and only rarely have dissections been made which failed 
to show the presence of an egg. Often the larva attacked thrashes 
about so violently that it and the parasite fall, but rarely does the 
parasite fail in its object. After ovipositing in a larva the female 
usually proceeds to another victim, but occasionally will oviposit a 
second time before leaving the caterpillar. She apparently does not 
examine a prospective host but attacks it whether it has previously 
been parasitized or not. This practice of occasionally placing an 
egg in a parasitized caterpillar is unfortunate as only very excep- 
tionally will more than one maggot develop within a single host. 
The parasite favors the posterior half of the caterpillar for oviposi- 
tion, but will oviposit in any segment of the body. 
The females of A. melanoscelus which issue from hibernating 
cocoons prefer to parasitize the first and second stage gipsy-moth 
larvae but will oviposit successfully in third-stage larvae if they are 
present. When the next or summer generation of adults appear, 
most of the gipsy-moth larvae are in the third stage. This is the 
stage most heavily attacked by this generation, although many 
fourth-stage caterpillars are successfully parasitized. Apanteles 
females of this generation often attempt oviposition in fifth and 
sixth stage larvee but are not so successful, for they are hindered by 
the long hairs of large larvae. 
There was considerable variation in the number of oppositions 
different individuals would make. Between 200 and 300 oviposi- 
tions per female were often obtained in these experiments. The 
greatest number of ovipositions secured by a single female of A. 
melanoscelus was 535. She actually had gipsy-moth larvae before 
her for 510 minutes, making these ovipositions a little faster than 
one a minute. 10 The parasite was allowed several oviposition periods 
each day and she would parasitize the gipsy-moth larvae as fast as 
they were introduced for from 30 to 60 minutes. The first clay the 
periods of oviposition were a little longer than during the follow- 
ing days. This female issued May 23 from its hibernating cocoon, 
but was not given an opportunity to oviposit until May 27, when 
10 This is about as fast as larvae can be introduced and withdrawn by the process used. 
Under more natural conditions, as found in the large breeding chamber, the females were 
often observed to oviposit 6 or 7 times a minute. 
