DANGER OF SPREAD OF GIPSY AND BROWN-TAIL MOTHS. 21 
that the moths have alighted upon their ships in great numbers in the vicinity of 
Boston along toward midnight on several occasions, and the introduction of the species 
at more than one seaport in Maine has been by means of vessels coming from the 
infested district rather than by direct flight. Of course, the brown-tail moth is carried 
in the caterpillar stage, just as is the gipsy moth, upon vehicles of different kinds 
passing through the infested region and upon the persons of pedestrians as well. In 
late May, 1906, the writer, in company with three other persons, walked through the 
woods in a region not far from Boston, and although the most careful efforts were made 
by each of us to pick the caterpillars from the clothes of the others, an hour or two 
afterwards, and many miles away by automobile, still others were found under the 
upturned trousers and lapels of coats and in other hidden places about garments. 
’ The eggs are laid by the moths soon after the flight begins, say in the latter part of 
July. They hatch during August and the young larve feed in clusters on the upper 
surface of leaves, skeletonizing them and causing 
the foliage to turn brown asif blighted. At first 
they feed upon the leaf which bears the egg 
mass, but soon wander to others, returning at 
night to the original leaf. When first hatched 
they are about one-twelfth of an inch long, and 
in five to six days shed their skin, increasing in 
length to one-fifth of an inch. 
Later the second molt occurs, although this 
sometimes does not take place until autumn 
within the winter web. Along in September 
they begin to spin their winter webs by drawing 
together a number of leaves with silk, and in 
each of these nests a large number of caterpillars 
stow themselves away for the winter. These 
webs or nests, composed of leaves and silk, widl 
average from 5 to 6 inches in length, and each 
will contain 200 or more caterpillars. The 
caterpillars feed until cold weather, and then 
all enter the web and close the exit holes. They 
are then about one-fourth grown. 
These winter webs (fig. 7) of the brown-tail 
moth are very characteristic, and there are 
practically no other insect structures common 
upon trees which may be mistaken for them. 
There are certain old webs of native species 
which might possibly, by the untrained eye, 
be considered to be those of the brown-tail 
moth, but these are empty in the winter time. 
Any web of this character and general size found 
during the winter which contains young caterpillars in any number is the web of the 
brown-tail moth. 
The following spring, as soon as the buds begin to appear upon fruit trees, these 
young, one-fourth-grown caterpillars issue from the overwintering nests and attack 
first the buds and blossoms and later the foliage. Apparently half starved by their 
long hibernation, they come out with voracious appetites, and the amount of damage 
done by them at this time is extraordinary. Old trees may lose all their buds, or, if 
the leaf buds and blossom buds burst, the foliage itself may be entirely destroyed at 
a later date. The growth of the larva is rapid, and it reaches full size and begins to 
spin its cocoon during the last half of June, transforming to pupa and remaining in 
this condition for approximately 20 days. 
453 
Fic. 7.—Winter nest of the brown-tail moth, 
containing 300 or 400 young caterpillars. 
(Original. ) 
