- 646 - 
velopod rapidly during 1938 1939 to ^ ■ point wtiere control measures seen 
impractical-# The .last previous epidemic iV this area occurred during the period 
1928-30. . ' ;' rr 
SCKEWOHM * - • • - • 
Losses from the sc reborn in the Southwest during 1939 were about average 
and were somewhat less than in 1938. Leas ddnage was noted, particularly in • 
Arizona, New Mexico, Oklahoma, and Kansas and also in central and eastern Texas# 
Louisiana had little trouble with the pest and apparently Mississippi was not 
invaded at all# In Kansas there was considerable trouble early in the spring, 
owing to infested cattle being shipped into the State from southern Texas, but 
after June 1 the infestation practically disappeared. In the vicinity of Menard, 
Tex., a close check on several rancher indicated an infestation of 3 • 57 percent 
of ali livestock in 1939 fl-s compared -ith 3*27 percent in 1938. 
The overwintering of the screwworn fly in numbers in Texas during the -'inter 
of 1938-39 was restricted mostly to a small area in Kinney and Val Vorde and the 
southern part of Ed-ards Counties by very drv conditions during the latter part 
of the summer of 1938 # and continuing through the winter and spring of 1939 * A 
winter peak population of flies (153 females), as determined by trapping, -'as 
recorded at Brackettville, Tex., in ‘December 1938 # On the escarpment of the 
Edwards Plateau in Texas comparative papula t ions Of s crewworn flies for the period 
January 1 to April 15 in 1938 and 1939 were 248 and 39» respectively# The spring 
population in 1939 reached a peak of 1,044 females in the trapping period, which 
ended June 30 at Brackettville, Migration is indicated to have roinfes ted the 
area east on the escarpment about 1 month later than normal and a light infestotio 
reached Lufkin, Tex., in the la- t days of August, Migration north into the Okla- 
homa area was only slightly slower than normal. The flies reached Buffalo, Okla#, 
late in August, but rone of the area south, to the Balcones escarpment was heavily 
infested, there being practically no .crises in much of the area during the entire 
summer# 
The very hot, dry summer of 1938 practically exterminated the fly south and 
east of Uvalde, Tex., on the Gulf Coast Plain to near the Gulf coast. This area 
nay have been reinfested durinv 1939 partly from the overwintering area at 
Brackettville and partlv from the ovorwint ring area about San Perlita, Tex. , 
on the lower Gulf Coast Plain. None of this area had any considerable spring 
peak. The highest peak of 196 females -ms reached on April 15 at San Perlita# 
In the general area between San Perlita and Brackettville areas no place is in- 
dicated to have had more than 50 adults per trap period during the summer or fall# 
A high fall peak was built up along the escarpment. This peak was reached with 
1,356 females per trapping period north of Brackettville on October 15 , and for 
the eastern escarpment at Kerrville on the sane date with 697 females. The peak 
population on the lower Gulf Plain was JO females at San Perlita on October 30, 
the number decreasing* to 35 on December 1. Other areas had less than 10 flies per 
trap period. 
The decrease on the escarpment has been slightly greater this fall than last — 
from 4,077 adults to 134 in the general trapping area from October 1 to December 
1— practically 97 percent. Last year the decrease -as from a peak of 1.736 females 
to 65 , or 96 percent, for the same period. At the first of December, 1939, there 
was a general infestation of about normal over the entire lo-er es-.arpment and a 
general light infestation over the entire Gulf Plain, Numerous screwworn infesta- 
tions occurred among new-born calves during the latter half of December in the 
Brady, Tex. , area. 
