554 
Journal of Agricultural Research 
Vol. XXin, No. T 
DESCRIPTION OP DARVA 
The full-grown larva (PI. i, D) is of typical chalcid form; widest at the middle, it 
tapers both cephalad and caudad; smooth and shining in appearance, white in color 
but muddy-looking from the contents of the alimentary canal, which is greatly dis¬ 
tended and appears nearly to fill the body cavity. The head is fairly prominent, bear¬ 
ing two tubercules and several small setae, mouth-parts consisting mainly of two 
chitinized mandibles (PI. i, C) 0.053 to 0.057 mm. in length; mesothoracic, meta- 
thoracic, and first 7 abdominal segments bearing a pair of spiracles. The thoracic 
segments are provided with 4 setae on each side. Abdominal segments 1 to 9, in¬ 
clusive, have a subdorsal and a sublateral row of setae on each side, 1 seta per segment 
in each row. The anal segment has a dorsal and ventral lobe, dorsal lobe has 4 setae, 
and ventral lobe has 2 setae. Length 2.7 to 3.0 mm., width 1.0 to 1.2 mm. 
PREPUPAL STAGE 
When full-grown the larva voids the entire contents of the alimentary 
tract. It becomes strikingly white in color and assumes a quiescent or 
prepupal stage. This stage normally lasts but a few hours, when the 
true pupal form is assumed. 
PUPA 
The pupa (PI. 1, E), is at first perfectly white in color but soon turns to a pale 
yellowish brown, the eyes and ocelli turning reddish, and the mandibles brown. 
As the pupa gets older the eyes turn a darker red, and the thorax becomes dark in 
color followed by the head. Finally the abdomen of the male becomes banded with 
black and that of the female entirely black. The sexes may be readily distinguished 
in this stage by the difference in size, the females being considerably larger than 
the males. Male: Length 1.45 to 2.0 mm., width 0.61 to 0.79 mm. Female: Length 
2.2 to 2.4 mm., width 0.90 to 1.0 mm. 
The pupal stage lasts for a period of from 6 to 7 days. The males 
usually emerge in 6 days, while the females take 7. In winter the pupal 
stage is considerably prolonged, sometimes as long as 30 days. 
HABITS OF ADULTS 
In order to test the effect of light and darkness on the activity of the 
parasites, experiments were conducted in which com infested with Sito- 
philus oryza was placed in containers from which the light was excluded. 
It was so arranged that the parasites could leave the lighted tubes in 
which they were placed and enter the dark containers at will. 
It was found that the parasites would enter the darkened containers 
in search of their prey without any hesitation, so that we may assume 
that their beneficial work will be carried on equally as well whether the 
corn is stored in the light or the dark. 
Female parasites were frequently observed to feed on the body juices 
of the weevil grubs. After jabbing the grubs with their ovipositors 
they lap up the exuding juices. 
PARTHENOGENESIS 
Unfertilized females kept under observation laid fertile eggs which 
invariably developed into males. These females lived as long as the 
average fertilized ones or longer but laid only about half as many eggs. 
NUMBER OF MALES AND FEMALES 
Males are apparently more abundant than females. Of reared speci¬ 
mens 60 per cent were males. 
