DIRECTION AND VELOCITY OF WIND. 39 
are in the same direction during the first half of June as in the 
month of May, so that little benefit would be derived from giving 
the additional data. 
For convenience the record of infestation has been divided into 
four periods (see map 1), viz: 
(1) The territory infested in 1900 at the time the work was dis- 
continued by the State of Massachusetts. 
(2) The territory found infested as a result of scouting operations 
after the work was resumed in the winter of 1905-6 by the State of 
Massachusetts. 
(3) The territory found infested up to and including the winter 
of 1908-9. 
(4) The territory infested at the present time, winter of 1911-12. 
The territory infested in 1900 when the gipsy-moth work was 
discontinued by the State of Massachusetts was confined to 34 towns 
and cities surrounding Boston, covering an area of about 359 square 
miles. None of the area was badly infested, but a very rapid in- 
crease of the pest took place as soon as efforts to check it were 
abandoned. The next two years developed few signs of increase 
in the insect, although in several localities it was somewhat abundant 
in 1902. An infestation was discovered in Providence, R. L, in the 
summer of 1901. In the summers of 1903, 1904, and 1905 the terri- 
tory in Massachusetts which had been most densely infested when 
the work was discontinued fairly swarmed with caterpillars, and, 
as little organized effort was made to check the insect, an excellent 
opportunity was offered for the small caterpillars to be spread by 
the wind. Map 1 shows the territory which was found infested by 
the scouting operations conducted by the State of Massachusetts, 
which were carried on during the summer and fall of 1905. The 
infestation had increased to such an extent that it covered 132 towns 
and extended from Portsmouth, N. H., to Buzzards Bay, including, 
as well, isolated colonies in Providence and Cranston, R. I., and Ston- 
' ington, Conn., a total of about 2,224 square miles. 
Undoubtedly the greater part of this infestation was the result 
of wind spread, therefore map 1 indicates the number of days the 
wind blew in each direction during the period when caterpillars 
I were in the first stage, and when the temperature and wind velocity 
were favorable to their dispersion. Eliminating the west wind from 
" consideration, which would take the larvae out to sea, it will be 
noted that, except for seven days when it was from the east and 
north, the direction of the wind would account in a general way for 
the infested region as shown by the map. It is probable that more 
area would have been found infested in southern New Hampshire 
in 1905 if it had been possible to scout the towns nearest Massa- 
chusetts, but there were no funds available for this purpose. 
