PCa ye 
‘shade-tree pests. Under 
Insects of Shade Trees and Their Control. 41 
worms attain full growth in July, leave the web, and crawl down the 
trunk of the tree to pupate. Late in August the year’s second crop 
of their tents is in evidence. 
Control—Natural agencies, and particularly parasitic and preda- 
cious insects, usually keep the fall webworm in check. When they 
become excessively abundant they are invariably attacked by a va- 
riety of insect enemies and by a veritable epidemic of diseases which 
destroy great numbers of the caterpillars, so that they are usually 
numerous not more than two years in succession. 
The most practical remedies against the fall webworm are the 
destruction of the cocoons, burning the tents, and spraying the in- 
fested trees with lead y 
arsenate (p.11). The 
methods to be employed 
are the same as those 
recommended for the tus- 
sock moth. 
WHITE-MARKED TUSSOCK 
MOTH.” 
How injurious.— The 
white-marked_ tussock 
moth is one of our worst 
favorable conditions it is 
capable of increasing to 
enormous numbers, and 
its caterpillars may com- 
pletely defoliate the shade 
and park trees of a com- 
munity. Excepting coni- 
fers, it attacks almost 
every variety of tree, and 
especially poplar, soft. me. 23--ran webworm: Moths and. cocoons. 
maple, elm, alder. birch, Natural size. (Howard.) 
and willow. It is most destructive in cities. The caterpillars are 
given to migration, and the cocoons made by them may be located 
in almost any place that offers some measure of shelter. It is not 
abundant every year, being in the meantime kept in check by natural 
agencies, principally parasitic insects. 
_ Signs of infestation—From September until the following spring, 
conspicuous, glistening white, frothy-looking eg@ masses (fig. 24, h) 
may be observed, mostly low down on the trunk of the tree or on the 
1 Femerocampa leucostigma S. & A, 
