416 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1958 
Board and the Animal Disease Eradication Division (Illustrated 
Descriptive Bulletin No. 1) and in Florida Information Office Tlus- 
trated Bulletin No. 2, issued November 1958 by the Florida Live- 
stock Board and the U.S. Department of Agriculture. The adult 
brood colony, consisting of thousands of flies (pl. 3, fig. 1), furnishes 
eggs to start the fly production. The larvae are reared in a medium 
consisting of ground meat and blood in large vats (pl. 8, fig. 2). The 
temperature of the medium is about 99° F., simulating body tempera- 
tures of the screwworm’s hosts. The pupae are placed in screen-bot- 
tom trays (pl. 4, fig. 1) and held at 80° F. for about 6 days. They are 
then exposed to irradiation in a cobalt-60 gamma-ray unit (pl. 4, fig. 2). 
The dosage is 8,000 roentgens, which assures sterility of both male and 
female insects. Several hundred irradiated pupae are then placed 
in special boxes, where they emerge in about 2 days. The flies from 
each box are liberated at intervals of about a mile from planes as- 
signed to various sectors in the eradication area (pl. 5, figs. 1 and 2). 
The number of flies released per square mile varies with the number 
of sterile flies available and abundance of screwworms in the natural 
population. 
The following are a few statistics which indicate the magnitude 
of the program. The screwworm rearing plant is designed to pro- 
duce 50 million flies per week. The sterile insects (both sexes) are 
released at the average rate of 1,000 per square mile per week in an 
area of 50,000 square miles. About 80,000 pounds of ground meat 
and 4,500 gallons of blood are required per week as larval food. 
Six cobalt-60 units are available to irradiate the pupae. Twenty 
airplanes are needed to distribute the flies. The staff consists of 
200 to 800 workers in the fly-production plant and about 50 inspec- 
tors keep check on screwworm abundance and on the results of the 
operation. <A group of scientists supervises the operations, and others 
are concerned with methods improvement. A quarantine line has 
been established along the Mississippi River for the inspection and 
treatment of animals to prevent screwworm establishment from in- 
fested hosts shipped from the Southwest. 
Results of the program will in time be published, but there is every 
indication that the objective, as on Curacao, will be achieved much 
more rapidly than we had dared to hope for. 
WILL THE STERILE-MALE METHOD PROVE USEFUL FOR CONTROLLING OR 
ERADICATING OTHER INSECTS? 
The successes against the screwworm on Curacao and in Florida 
have stimulated interest by biologists to explore the sterile-male 
method for controlling other insects. There is reason to believe that 
this new biological-control technique might prove practical for eradi- 
cating or controlling certain other major pests. A number of require- 
