THE GIPSY MOTH ON CRANBERRY BOGS. 3 
cranberry bogs become infested with gipsy moth larva?. In view 
of the fact that cranberry foliage is not a very favored food which 
gipsy moth larvae seek by choice, and as the bog does not offer 
favorable conditions for reproduction of the moths from year to 
year, it is obvious that wind dispersion is an important, if not the 
most important, factor to be considered in studying the infestation 
of bogs. 
WIND DISPERSION OF GIPSY MOTH LARV^. 
HISTORY. 
The first investigations of wind dispersion of the first-stage gipsy 
moth larva? were made in 1910 by A. F. Burgess and recorded in Bul- 
letin Xo. 119 of the Bureau of Entomology. These investigations 
established the fact that the young gipsy moth caterpillars, soon after 
they emerged from the egg, were carried considerable distances by 
the wind. This Avas the first indisputable explanation of the origin 
of isolated infestations in woodlands, as well as those that were 
frequently located in territory outside of the known infested area. 
The spread of this insect in a northeasterly direction year by year, 
it was found, was due to the fact that the wind usually blows from 
the southwest at the time when the young caterpillars first reach the 
tops of the trees. 
In 1913-14 C. W. Collins carried on a series of experiments to de- 
termine the distance young caterpillars would be carried by the wind. 
The results of these experiments are recorded in Bulletin No. 273 of 
the U. S. Department of Agriculture, in which it is shown that under 
favorable conditions the small caterpillars were carried 13J miles. 
Later experiments have demonstrated that they may be carried 20 
miles, and it is probable that under the most favorable conditions the 
spread is even greater. 
SELECTION OF A BOG FOR EXPERIMENTAL PURPOSES. 
Several bogs in the cranberry region were examined and the one that 
seemed best suited for the experiments was in the northern part of 
Carver, Plymouth County, Mass. This bog was approximately oval in 
form, about 3,6.00 feet long and 2,000 feet across at its widest part. The 
bordering uplands were typical of the region, consisting of eleva- 
tions, from 10 to 50 feet in height, well wooded with pine, oak, birch, 
and some maple, with a few stands made up mainly of oak and birch. 
Egg clusters of the gipsy moth were found in these bordering wood- 
lands, and were particularly plentiful on the western border. Some 
sections of this area were already in bog, one portion was in process 
of reconstruction, and the remainder was the bed of a pond that had 
recently been drained for the purpose of converting the whole area 
into one large cranberry bog. (PL I, Fig. 2.) 
