vp PARASITES OF THE COTTON BOLL WEEVIL. 
1. Inasmuch as the parasites are known to attack the weevil in 
its first generation in a newly infested locality, it may be expected 
that by releasing the proper parasites in a given locality the per- 
centage of parasitism may be increased in a very short time. Such 
a case was actually obtained by the release of Bracon mellitor at 
Dallas, as described in the section on propagation. 
2. Dryness and sunlight assist attack by the chalcidoid and bra- 
conid parasites of the weevil, as proved by the following considera- 
tions: (It is, of course, to be understood that this conclusion may hold 
only for those species and regions studied. In fact two or three of 
the minor species, such as the tachinids, give promise of doing most 
favorable work under directly opposite conditions in regions so far 
unstudied. ) 
a. Stages in hanging forms are, as a rule, parasitized to a higher 
degree than those in fallen forms. 
b. Stages in fallen forms on prairie land are generally more highly. 
parasitized than those in wooded country, although frequently hang- 
ing forms in wooded country are more highly parasitized than those 
in prairie land. 
c. Fallen and hanging forms on unshaded ground are more highly 
parasitized than those on shaded soil. 
These facts give an added importance to certain cultural methods 
already advocated, viz: 
a. That the rows should be far apart, in order to allow the sun to 
dry the squares on the ground. 
b. That determinate varieties should be planted in order to give 
additional heat and light for the parasites during the cooler autumn 
months. 
That, as indicated by the present studies, dryness seems to be a 
most favorable condition for attack by hymenopterous parasites is 
quite natural, as these delicate little insects are very fond of sunlight 
and warmth. 
II. Propagation Work. 
1. INTERIOR WORK — TRANSFER OR ARTIFICIAL PROPAGATION OF 
PARASITES. 
It has not been a difficult matter to breed the parasites of the boll 
weevil. There have been used in this laboratory four distinct 
methods of obtaining parasites, all of which served the purpose for 
which they were used. In all cases where definite records of per- 
centage, length of stages, or nature of parasitism were required 
there has been a careful examination of each form (square or boll), 
and those forms containing parasites, or sometimes only the para- 
site and its host, were placed in individual pill bottles, numbered, 
recorded, and placed in trays for daily observation. A somewhat 
t 
