82 ANNTAL KKI'ORTS OF DE FARTHEST OF AGBH l I/riTJ:, 1940 
combined with close spacing and withholding of Kate-season irriga- 
tion water, produced less than one-third as many worms during the 
season as did the slow-maturing variety generally used in the irri- 
gated sections of the Southwest. Of the various winter cultural 
pract ice- for reducing the survival of hibernating larvae 1 , deep plow- 
ing early in the winter followed by irrigations again gave the best 
control. A da te-of -pi anting experiment in winch cotton was planted 
March 28, April 20, and May 15 under a Large cage showed that 
although delaying planting decreased the initial infestation because 
moths emerged before squares were available for larval food, it 
also increased the populations entering hibernation in the fall owing 
to later maturity of the crop. 
Of the 33 domestic and foreign strains of okra planted at, Presidio, 
Tex., to determine whether any were immune to pink bollworm 
attack, 32 strains produced pods and all became infested. Larvae 
were found to attack the flower hud- and L-day-old pods, and Larvae 
that were immature at the time pods were collected developed into 
normal moths when stored under favorable conditions for insect 
development. 
Special attention was driven to biological studies to determine how 
and where the pink bollworm passes the winter in the lower Rio 
Grande Valley. Larvae were found in green fruiting forms of 
cotton until all the cotton was killed, about the middle of January 
1940, and again when pods became available in May. There seems 
little doubt that breeding will continue throughout the winter if 
normal conditions prevail and food is available. Some larvae en- 
tered the resting stage as early as Jul} 7 , but the time of moth emergence 
could not be determined because of quarantine restrictions. Re-t- 
ing-stage larvae were found in old bolls and locks of cotton on plants 
and on the soil surface, or buried in the soil, throughout the 
winter and until April 1940. No larvae were found in loose 
cocoons in the soil as is the case in the Big Bend. About 50 species 
of malvaceous plants occur in the region but none was found in- 
fested except okra and Turk's cap (Malvaviscus drumtnondii) . 
Large quantities of seed pods of Hibiscus cardiophyUus, a known 
host, were examined with negative results. 
Rearing of M ic rul> racun kirk pat rick i Wilkn.. which was discon- 
tinued in 1938 after this parasite's failure to become established at 
Presidio, was resumed through breeding stock obtained from Egypt 
by the Division of Foreign Parasite Introduction. This species 
readily attacks boll weevil larvae under laboratory conditions, and 
liberations will be continued at Brownsville, Tex., where both the 
pink bollworm and the boll weevil OCCUT and conditions are more 
favorable for establishment than in the Big Bend. A total of 
306,500 adults of ChelonUS blackburin Cam. were liberated during 
the year in the Presidio and lower Rio (irande Valleys of Texas. 
A heavy mortality occurred in the cocoons of Microbtdook it'<<ji<>ru- 
fum Cush. held in cold storage over winter, and only one colony 
was liberated at Brownsville. 
PINK BOLLWORM CONTROL AND QUARANTINE ENFORCEMENT 
The outstanding accomplishment in connection with pink bollworm 
control <lniing the L939 season was in connection with cottonfield 
clean up nil approximately -100,000 acres in the southern part of Texas. 
