2 BULLETIN 273, U. S. DEPARTMENT OF AGRICULTURE. 
To secure further information, the writer, under the direction of 
Mr. A. F. Burgess, commenced a series of experiments in the spring 
of 1913 and continued them throughout the following year. 1 
PREVIOUS INVESTIGATIONS ON DISPERSION OF THE GIPSY MOTH, 
Many investigations of various sources of spread of this insect were 
conducted during the early nineties by Forbush and Fernald and 
published by the Massachusetts State Board of Agriculture in 1896. 
It was found that frequent teaming in and out of the original infested 
areas (Medford, Boston, and towns closely surrounding) by vehicles 
transporting larvae that dropped from infested shade and roadside 
trees was largely responsible for the general local spread during those 
years. It was also suggested that the larvae were occasionally trans- 
ported by the wind to distances of perhaps 100 yards, but no further 
observations were made at that time to substantiate this theory. 
Numerous ways and means of local spread, such as by birds, animals, 
and man, are treated in this valuable report. 
In the spring of 1910 Mr. A. F. Burgess began a series of experiments 
on dispersion of the gipsy moth the account of which is published as 
Bulletin 119 of the Bureau of Entomology. A few small experiments 
were made in the laboratory by releasing silk-suspended first-stage 
gipsy-moth larvae in front of an electric fan, and it was foimd that 
they soared to a distance of 20 to 30 feet in the air before falling. 
This led to more extensive experiments conducted under out-of-door 
conditions. Screens constructed of poultry wire and covered with 
tanglefoot were stationed at given distances from souroes of infesta- 
tion and watched for catches of larvae. On a small screen stationed 
on the marshes near Lynn, Mass., newly hatched larvae were caught 
that had been carried 1,833 feet by a west wind at a velocity of 7 to 
19 miles per hour. 
Numerous records were compiled to show the relation of tempera- 
ture, wind velocity, and wind direction to the general trend of spread 
as it has progressed from the original center, Medford, Mass. It was 
clearly demonstrated that the prevalent southwest winds following 
the hatching period of the eggs each year has resulted in the more 
rapid dispersion of the moth to the northeast than in any other direc= 
tion. Large woodland areas were scouted in various towns, the 
data of which were compiled and show the extent to which the wind 
is responsible for the remote and numerous colonies located. The 
automobile is also included in this report, as a very important factor 
in carrying the caterpillars both locally and for long distances. 
i The writer is indebted to Mr. L. H. Worthley and Dr. J. W. Chapman for cooperation and helpful 
suggestions; to Messrs. C. E. Hood, F. W. Graham, and Harry Blaisdell for the collection of field data; 
to Mr. H. A. Preston for the preparation of photographic illustration s, and to others of the laboratory 
force who contributed in various ways. 
