1907 ENTOMOLOGICAL SOCIETY. 29 



"The biology of the insects is briefly this: in the case of the Gypsy 

 Moth the eggs hatch about the last week in April, the caterpillars, which 

 feed on all kinds of foliage are full-grown about the middle of July. Words 

 cannot describe the havoc wrought by these caterpillar swarms. In early 

 July of the past year, some 3,000 acres of mixed woodland in Eastern Mas- 

 sachusetts were defoliated by the gypsy caterpillars, and left as bare as in 

 winter. They feed on all trees, nearly all crops, and often invade houses 

 by the hundred. No more pitiful and at the same time disgusting sight 

 can be conceived than a gypsy moth outbreak at its height. No wonder 

 that in the olden days before the science of economic entomology was dreamt 

 of, people so afilicted sought a remedy through pr yer, or that they regard- 

 ed the pest as a device of the Evil One. The pupal stage extends to about 

 the 1st of August, while the moths are from a week to ten days in deposit- 

 ing their yellow, hair covered egg clusters. The egg clusters are laid on 

 tree trunks, stone walls, houses, fences, and old tin cans — in fact, in all 

 places where the caterpillars may go to pupate. The female seldom moves 

 far from the pupa case from which she has emerged. 



"With the Brown-tail Moth the eggs hatch about the middle of August, 

 and the young caterpillars feed at the tips of the twiars, preferably those oi 

 fruit trees, until the approach of cold weather, when they draw together the 

 leaves from which the epidermis has been removed, and spin them up with 

 a most tenacious web, thus forming a hibernaculum within which they 

 congregate to the number of two or three hundred, and thus safely pass 

 the winter. The same warm weather that causes the buds to swell the fol- 

 lowing spring brings out these small caterpillars, which feed on buds, blos- 

 soms, and leaves, and when abundant, often strip entire orchards and 

 groves of oak. Aside from the damage to trees the hairs of the caterpillars 

 are intensely poisonous and cause a severe and most painful eruption of 

 the skin whenever they come in contact with it. By the middle or latter 

 part of June, the insects are fully grown when they spin cocoons, often in 

 masses at the tips of twigs, on fences, and even house walls. From the 12th 

 to the 15th of July the white, brown-tail moths emerge, fly freely, mate 

 principally by night, and the females at once begin the work of oviposition. 

 Some four or five days are consumed in this process by which time the 

 brown, elongated, hair-covered egg masses have been securely attached to 

 leaves at the tips of twigs. Hatching takes place in from three to four 

 weeks. 



"For remedial measures against the Gypsy Moth we have found spray- 

 ing done in the early caterpillar season the most valuable of any single 

 method. Power sprayers, throwing the spray under heavy pressure have 

 proved the most economical, as far as street tree and orchard work is con- 

 cerned, and also, in those woodlands which are accessible to heavy machines. 

 In woodland spraying, however, the thinning of trees, and cutting out of 

 underbrush is an indispensable prerequisite, and this Dreliminary work is 

 usually done during the previous fall and winter months. In spraying 

 against the Gypsy Moth, arsenate of lead paste at the rate of 10 pounds to 

 100 gallons of water gives the best results. On rough or rocky hillsides, and 

 in other places where the power sprayer cannot be worked to advantage, 

 hand spray pumps are freely used with good results. As the caterpillars 

 approach maturity, they show considerable resistance to poison, and further 

 acquire the odd habit of feeding by nisrht and hiding by day in sheltered 

 places. Taking advantage of this habit we band the infested trees with 

 strips of burlap, beneath which the caterpillars assemble in the early raorn- 

 ins" hours, and where they may be destroyed at any time by hand during 



