12 ANNUAL REPORT* OF DEPARTMENT OF AGRICULTURE, 1940 
FRUITFLY INVESTIGATIONS 
The results of fumigation studies in Hawaii with methyl bromide 
have permitted authorization for shipment of products to the main- 
land after fumigation. A -pray giving good control of the melonfr? 
in Hawaii was developed. A potent lure for the meionlly was found. 
Svnergistic action in connection with repellents for the Mexican 
fruit flv was demonstrated. Studies on the fruitfly attacking citrus 
in Puerto Hico have resulted in a le-sening of the restrictions which 
apply to the citrus industry in Puerto Rico from the standpoint of 
domestic quarantines. 
MEXICAN FRUITFLY CONTROL 
INFESTATIONS 
Early in January it appeared that another serious fruitfly infes- 
tation was in prospect for the lower Rio Grande Valley. Traps 
indicated the presence of a considerable fruitfly population which 
it was believed would cause a general heavy infestation he fore the 
season was over. The low temperatures late in January, however, 
disrupted normal fruitfly activity, and only '21 percent a> many 
groves were found infested as were known to have been mfested 
during the preceding season. The fly population was mounting when 
harvesting was completed on April 30, but as no fruit was available 
for oviposition, the number of plantings infested was reduced 
accordingly. 
Table 1 shows, for the years 1935-40, the number of infestations 
in relation to the number of flies trapped and the date the harvesting 
season closed. 
Taqle 1. — Infestations of the Mexican fruitfly in Texas, (935 t940 
Fiscal year 
Flies 
trapped 
Larval 
infesta- 
tions 
Harvest- 
ing 
closed 
Fiscal year 
Flies 
trappt-d 
Una! 
infesta- 
tions 
H ir\ rat- 
ing 
eh. si'd 
1935 
Number 
367 
251 
4,714 
Number 
30 
5 
1.062 
Apr. 2 
Mar. 31 
Do. 
1938 
Nu mber 
712 
13. 687 
6, 157 
Nu mber 
218 
2. 141 
i 582 
Apr. m 
M.n U 
: June 15 
Apr. 30 
1936 
1939 
1937 
1940 
I For grapefruit. 
1 For oranges. 
1 Including 4 infestations in fruit of 1939. 
STERILIZATION 
There are two approved fruit-sterilization processes. The low- 
temperature method consists of lowering the inside fruit temperature 
to :'.o°-31° F. and holding it there for L5 days. This method is used 
for a relatively small amount of fruit, as considerable more time is 
required, and the process is somewhat more expensive than the high- 
temperature t reatment. 
The vapop heat method consists of raising the inside fruit tempera- 
ture to L10 V. and holding this for 6 hours. The approach and 
sterilization periods require a minimum of 11 hours, and the entire 
process musl !><• carried oul in specially adapted fruit rooms. 
