11 
Fig. 7. Linden tree in a park in Chicago, defoliated by larvae 
of White-marlied Tussock-moth (Hemerocampa leucosCigtna). The 
few leaves on the tree have all appeared since the defoliation. 
white patches about an inch in length, on the tree trunks, in the 
crotches of the larger branches, or in other more or less sheltered 
places, such as the edges of weather-boards and the under sides of 
the eaves of porches. Conspicuous objects at first, their color, under 
exposure to the sooty air of Illinois towns, is soon deadened to a 
dirty gray. The caterpillar begins to hatch from the over-wintering 
Qgg masses about the middle of June in Chicago (June i8 in 1909) 
and gets its growth in about a month. Feeding at first on the under 
side of the leaf, which it skeletonizes by eating off the soft tissue, 
it later eats inward from the edge of the leaf, devouring everything 
except the principal veins. 
