APANTELES MELANOSCELUS GIPSY-MOTH PARASITE. 21 
With this arrangement all of the light entering the chamber comes 
from beneath, through the glass bottom of the chamber and through 
the cloth-covered bottom of the tray. Five minutes after the cham- 
ber is in this position practically all of the Apanteles have left the 
top of the chamber and are found dispersed over the bottom of the 
tray, where the gipsy-moth larvae are feeding and crawling. The 
parasites begin ovipositing in the caterpillars immediately after 
they have been attracted to the bottom of the tray. 
When the caterpillars have been exposed to Apanteles melano- 
scelus for a sufficient period the operations are reversed ; the cham- 
ber is placed on a black-covered surface with the end of the cham- 
ber opposite the end where the tray is to be removed, facing the sun. 
Light is now admitted by removing the black paper over a space of 
6 or 7 inches, as shown in Plate V, B at L. In a few minutes most 
of the parasites will congregate in the top of the chamber at the 
light end. The opposite end of the chamber can now be opened 
without danger of any of the parasites escaping. The tray is with- 
drawn slowly, care being taken that all of the Apanteles have left 
it. If any still remain, they will fly to the light end of the chamber 
when disturbed by touching them with a small camel's-hair brush. 
As soon as the tray has been removed another one is introduced and 
the process is repeated as long as the supply of Apanteles melanoscelus 
lasts. The larvae parasitized in this manner are fed in the trays until 
the parasite maggots issue. The resulting cocoons are removed each 
day for colonization. 
A breeding chamber stocked with 300 adults of Apanteles melan- 
oscelus^ with the sexes equally divided, can be used about one week. 
Each tray should contain about 10,000 first-stage gipsy -moth larvae. 
The period of exposure of the larvae to the parasites varies with the 
temperature and time of day. The parasites are most active during 
the middle of the clay. The larvae were enclosed in the chamber about 
two hours during this part of the day. Earlier in the morning and 
later in the afternoon the larvae were exposed for about three hours. 
An average of about 1,000 parasite cocoons were removed from each 
tray. Undoubtedly many more than a thousand larvae were para- 
sitized in each tray, but there is always a certain amount of unavoid- 
able mortality of first-stage larvae in feeding trays. Many of the 
larvae are weak and do not get to the food and many are injured when 
the trays are cleaned and the larvae fed. 
SUCCESS OF COLONIES AND DISTRIBUTION OF A. MELANOSCELUS. 
Records of the success or establishment of colonies liberated and 
of the distribution of the parasite are obtained by collecting host 
material from the field and rearing the parasite from these larvae at 
the laboratory, or by collecting the cocoons of the parasite in the 
field. 
