22 BULLETIN 273, U. S. DEPARTMENT OF AGRICULTURE. 
Considering the great numbers of larva? taken in these experiments, 
there can be no doubt that the wind is almost wholly responsible for 
the general spread of this insect in New England, notwithstanding 
the fact that many of the former publications teem with explanations 
of possible accidental or artificial spread by man and animals. The 
recent estabhshment by the Federal Horticultural Board of a quaran- 
tine on lumber products, Christmas trees, nursery stock, and stone 
moving from the infested territory, until inspection has been made, 
has greatly relieved the danger of a general distribution of the gipsy 
and brown-tail moths over the United States, but the sources of dis- 
persion of the gipsy moth by the wind can only be lessened by the 
effectiveness of the parasites and predaceous enemies, together with 
hand methods of control. To prevent continual spread by the wind 
into new territory the badly infested areas near the border must be 
brought under control either by natural enemies, or hand methods, 
or both. Natural enemies, however, are now playing an important 
role in the control of this insect in the greater area of the inside 
infested territory. 
The larva? are sufficiently active and allow themselves to be trans- 
ported by the wind at temperatures of 55° F. and above, and have 
been caught at wind velocities varying from 2 to 23 miles per hour, 
although more active spread takes place when the temperature 
ranges from 65° to 85° F. and when the velocity reaches 8 miles or 
more per hour. Larva? are removed from their support and carried 
by sudden gusts of wind, whether they spin or not, when the tempera- 
ture reaches 50° to 55° F., at which temperatures they often start 
crawling. 
The records also show that larva? have been caught at times when 
winds were blowing from all directions except the north — only a very 
few coming from the east, but the location of the screens along and 
near the coast materially affected this condition. By far the larger 
numbers were borne by combinations of the west winds as indicated 
on the screen at Merrimac, Mass., which was surrounded by a general 
infestation. 
The general progress of the species since its establishment at 
Medford, Mass., at the rate of 5 miles per year to the northeast and 
at the rate of 3 miles per year westward from Providence, R. I., since 
its first appearance there in 1901 tends to verify the data that have 
been collected in connection with the screen experiments. 
BIBLIOGRAPHY. 
1893. Wachtl uxd Korxauth. Beitrage zur Kenntniss der Morphologie, Biologie 
und Pathologie der Xonne (Psilura monacha). In Mittheilungen aus dem 
forstlichen Yersuchsvesen Osterreichs, v. 16, 38 p., 3 pi., 8 fig. 
1894. Cholodkoysky. N. Ueber die sogenannten " Aerophore" der Xonnenraupe. 
In Forst-naturw. v. 3. no. 5, p. 240-243, 1 fig., May. 
