120 A M. \\T\L OF FORFSTKY 



FOREST "lY.xr C\\ IKKIMLI.AR ! OR MAPLE WORM (Malacosoma 



<l is stria}. 



Form oj Damage. A few years ago this insect caused a great 

 deal of damage throughout the northeast by defoliating sugar- 

 maple trees. Many sugar orchards were completely stripped of 

 leaves by the caterpillar, resulting in the death of numerous 

 trees, and an injury to sugar productivity which has not yet 

 been full}- compensated, after a period of ten years. The defo- 

 liation occurs for the most part in the early summer. While 

 the insect prefers the foliage of the maple, it does not confine 

 its ravages to this tree, but eats the foliage of oak, linden, locust, 

 peach, plum, cherry, apple, elm, poplar, birch and some of the 

 shrubs. 



Appearance. The damage is done by the caterpillar which 

 is blue-headed, with a line of silvery diamond-shaped spots 

 down the middle of the back. When not feeding, they assemble 

 in clusters on the sides of the larger limbs and trunks. This 

 inject may be distinguished from the common tent caterpillar, 

 Malacosoma americana, by the fact that it does not spin a con- 

 spicuous web tent as does the latter. The egg belts containing 

 about 150 eggs encircle the slender twigs and have a brownish 

 protective covering. The white or yellowish-white cocoons are 

 spun in the leaves on the tree or on the ground, in crevices of 

 the bark, under stones, in fence corners, etc. In the cocoons are 

 dark-brown pupas. The moths are light, buff colored and active. 

 The males are smaller than the females and of rich coloring. 



Life History. This insect passes the winter in the egg stage 

 as a well-developed larva. In the warm weather of spring the 

 young caterpillars emerge and await the unfolding of the leaves. 

 As the young increase in size they molt leaving their cast-off 

 skins on the bark. The larvae are found in clusters on the 

 limbs when not feeding. When the limb is jarred they are 

 easily knocked off. Early in June when the caterpillars are 



1 See New York State Museum Memoir 8, "Insects Affecting Park and Wood- 

 land Trees." 



