48 MAINE AGRICULTURAL EXPERIMENT STATION. 



REMEDIAL MEASURES. 



Trees well protected with arsenical sprays will not need other 

 treatment for fall web worm, for the poisoned leaves will be 

 drawn into the web for food. In many cases the simplest 

 means for combating them is to keep close watch upon the trees 

 and clip off and burn the web when it is still small. Even the 

 full sized web can be pruned off from trees not valuable, but 

 in the orchard there is, of course, no excuse for allowing them 

 to remain until large branches are involved in the web. The 

 web may be effectually drenched with a strong washing powder 

 solution or kerosene emulsion, during the day when the greatest 

 number of caterpillars are within. 



Orchard Tent Caterpillar. 

 (Malacosoma americana.) 



Encircling the twig of apple, plum, and wild cherry trees is 

 frequently found a glistening brown mass about three-fourths 

 of an inch in length (fig. 36). 



From such an egg cluster hatch in the spring from two hun- 

 dred to three hundred caterpillars, which live in a colony and 

 construct a whitish tent-like web in the angle of two convenient 

 branches. It is the habit of the tent caterpillars to pass their 

 time when not feeding, particularly at night and during cold or 

 stormy weather, within the tent which they enlarge as their own 

 rapid increase in size calls for more room. During the warm 

 sunny hours of the day they leave their protection and feed 

 voraciously, defoliating the branches in the vicinity of the tents. 

 One colony is enough to denude a young tree or several large 

 branches of an old tree. 



The tent which is at first a delicate filmy silken web becomes 

 by the time the caterpillars are full grown a structure two feet 

 or more in length, unsightly with the accumulation of molted 

 skins and other rubbish. 



The full grown caterpillar is nearly two inches long. It is 

 slender, dark, and velvety with numerous soft golden brown 

 hairs upon the body. A white stripe marks the middle of the 

 back, while the sides are streaked irregularly with white or yel- 

 low. Along each side of the dorsal white line is a row of trans- 

 verse pale blue spots. 



