42 MAINE AGRICULTURAL EXPERIMENT STATION. I9OO. 



The caterpillars are quite gregarious up to the later stages of 

 their growth, when they disperse to some extent ; but when they 

 occur only in moderate numbers, they retain their gregarious 

 habits to a greater degree than when they are very abundant, 

 since in this case the supply of food is soon exhausted and they 

 are forced to migrate. When these caterpillars molt they gather 

 in masses on the branches and cover themselves with a scanty 

 mass of silk. When preparing to change to the pupal stage 

 several of the caterpillars spin up in a common cocoon within 

 the leaves at the tip of the branches. When numerous, they 

 frequently pupate in masses under fences and clapboards, or on 

 the trunks and larger branches of the trees. 



The webs of the brown tail moth should not be confounded 

 with those of the tent caterpillar or the fall web worm. They 

 may be distinguished from those of the tent caterpillar by being 

 placed at the tips of the branches, while the tent caterpillar con- 

 structs its tent in a fork of the limbs. This latter insect rarely, 

 if ever, attacks the pear which is a favorite food plant of the 

 brown tail moth. The fall web worm, while often found on pear 

 trees, spins a large open web at the ends of the branches and 

 feeds within this web. This insect does not appear until after 

 the brown tail moth has ceased to do damage. 



Precautions. This pest does a great amount of damage in 

 Europe where laws are enacted to hold it in check. The Com- 

 monwealth of Massachusetts has enacted a law looking to its 

 suppression in that state and made an appropriation and put the 

 matter into the hands of the Gypsy Moth Commission. Now 

 that it is probably locally established in Maine immediate action 

 should be taken to prevent its spreading. A careful inspection 

 should be made of the localities where it has been found. 



