120 
able, as the}^ are easih' handled and the larv^ee thrive on them. With 
such an arrangement the food can readil}^ be changed and the bollworm 
examined whenever desired. B}^ using this method large numbers of 
parasites were bred out at the laboratory. 
The habits of the bollworms in feeding on corn are such that they 
are well protected from parasites after the first few days of their life, 
during which time the}^ have been boring down through the silk into 
the ear. When once well inside the ear it is practical!}^ impossible for 
parasites to reach the larva, unless it should leave the ear, which is 
ver}^ rarely the case. These conditions explain the small percentage 
of parasites shown in the following table: 
Table XLYII. — Percentages of lanw parasitized on corn, 1904. 
Date col 
lected. 
May 15 
May 30 
June 1 
June 14 
June 26 
July 14 
Aug. 18 
Sept. 10 
Sept. 10 
Sept. 12 
Sept. 30 
Locality. 
Hempstead, Tex. . 
Dallas, Tex 
Ladonia, Tex 
Paris, Tex 
Corsicana, Tex . . . 
Paris, Tex 
do 
Batesburg, S. C. . . 
Pine Bluff: Ark... 
Montgomery, Ala . 
Paris, Tex 
Average . 
Size of larvse. 
Miscellaneous , 
FuD -grown 
Miscellaneous 
Large •. . . 
Miscellaneous . 
do 
Large 
do 
Miscellaneous 
Large 
Miscellaneous 
collected. V^;^ 
Number 
18 
45 
19 
75 
35 
25 
105 
34 
22 
34 
30 
Number 
para- 
Per cent 
para- 
sitized. 








4.5 
3.0 
3.0 
Feeding on cotton, larvae are much more exposed to the attack of 
parasites, as they must move about in search of fresh squares or bolls; 
and even when partiall}^ hidden within a square or boll a larva is not 
completely immune. The following table shows very clearl}^ the 
greater proportion of parasites on cotton as compared with corn: 
Table XLYIII. — Percentages of larvx parasitized on cotton, 1904- 
Date col- 
lected. 
Locality. 
' Size of larv?e. 
Number 
collected. 
Number 
parasi- 
tized. 
Per cent 
parasi- 
tized. 
Aug. 20 
Paris, Tex 
184 
40 
104 
13 
31 
27 
53 
9 
16.75 
Aug. 25 
Aug. 31 
do 
67.50 
do 
Miscellaneous 
51.00 
Sept. 16 
Tupelo, Miss 
Small 
69.00 
51.00 
From these data it is evident that practically one-half of the larvae 
of the August brood are destroyed b}" parasites. This is especially 
important when Ave recall that it is this brood which causes the greatest 
damage to cotton. The insect responsible for this wholesale elimina- 
tion is a small hymenopteron belonging to the family Braconidse. It 
is more fully treated in the following pages. 
