February, '14] BURGESS: GIPSY AND BROWX-TAIL MOTH 85 



tion on the trees concerned. Areas are now under observation in 

 Maine, New Hampshire, and Massachusetts. 



Food Plant Work. — This work is in charge of Mr. F. H. Mosher, 

 and is carried on during the summer at the laboratory in Melrose 

 Highlands, Mass. Caterpillars of the gipsy moth are fed on selected 

 food plants and accurate records are kept of their ability to survive 

 and their preference for the different species of trees Avhich are common 

 in New England. A temporary sub-station for conducting a duplicate 

 set of these experiments has also been maintained and during the 

 past season was in charge of Mr. R. Wooldridge. The information 

 secured by feeding the caterpillars of the gipsy moth in each cater- 

 pillar stage is carefully compared each year with the results of the 

 observations made in the field points above mentioned, and informa- 

 tion has already been secured which can be used for thinning wood- 

 lands so as to leave the trees which are least subject to attack. 



Dispersion Work.- — ^This project is being carried on by Mr. C. W. 

 Collins, and consists of an extensive study of the factors responsible 

 for the natural and artificial spread of the gipsy moth. A large amount 

 of data has been secured on the temperature and field conditions most 

 favorable for the spread of this insect, and it has been demonstrated 

 that the newly hatched caterpillars can be carried long distances by 

 the wind. 



Disease Work. — Investigations on the wilt disease, w^hich attacks 

 the gipsy moth caterpillars and destroj^s large numbers of them in 

 bad infestations, are being conducted in cooperation with the Bussey 

 Institution of Harvard University. A large number of experiments 

 are being conducted at that Institution by Mr. R. W. Glaser, who is 

 working under the supervision of Dr. W. M. Wheeler. Check experi- 

 ments to determine the relation of food plants to the development of 

 the wilt disease were carried on by Mr. J. ,J. Culver, and an extensive 

 series of field observations was made by Mr. A. W. Young during the 

 summer of 1913 to secure information concerning the relation of 

 temperature and humidity to the development of the disease. 



Secondary Insect Work. — In many sections where trees have 

 been defoHated by the gipsy moth they are attacked by the bark 

 borers. Oak trees suffer very seriously in this respect, and an investi- 

 gation is being carried on in cooperation with Dr. A. D. Hopkins, who 

 has charge of the branch of forest insects of the Bureau of Entomology, 

 to secure more information along this hue. Mr. H. A. Preston is 

 . working under his direction in making a study of the life history and 

 habits of the principal boring insects concerned, and is carrying on a 

 number of experiments to determine whether this pest can be con- 

 trolled economically. 



