GIPSY MOTH AND BROWN-TAIL MOTH. 27 



towns adjoining the border in order that wind spread into the ter- 

 ritory that already has been treated may be prevented. 



In town or city work the bureau advises that carefid attention 

 be given to woodland infestation or isolated trees, particularly if they 

 are located on high elevations immediately outside the residential 

 area, as such colonies may furnish a supply of caterpillars which will 

 1)0 distributed thi'oughout the town after it has been cleaned. 



Under present conditions, owing to the decrease in the severity 

 of gipsy-moth mfestation in most sections, spraying becomes an eco- 

 nomical means of treatment and in some cases is used exclusively 

 for control. 



A great amount of experimental work has been conducted in order 

 that better methods of controlling these insects may be determined. 

 The introduction of natural enemies from Europe and Japan has pro- 

 ceeded systematically and good results are being noted in many locali- 

 ties. A systematic study of the wilt disease, which attacks gipsy-moth 

 caterpillars in the field, is being made in cooperation with the Bus- 

 scy Institution of Harvard University. Silvicultural investigations, 

 which have for their purpose the adoption of better methods of forest 

 management which wiU assist in the control of these pests, are being 

 carried on in cooperation with the Forest Service of this depart- 

 ment. This work is conducted by Mi-. George E. Clement. 

 • The entire infested area — 20,211 square miles occupied by the 

 gipsy moth and 36,6<S4 square miles occupied by the brown-tail 

 moth — has been placed under quarantine by the Federal Horticultm-al 

 Board, and shipments of nursery stock; lumber, cordwood, and other 

 forest products and stone and quarry products are not permitted to 

 leave the territory unless they have been inspected and are accom- 

 panied by a certificate stating that they are free from infestation. 

 This work is designed to prevent the spread of the insects for long 

 distances and is being administered by Mr. D. M. Rogei-s. 



COOPERATIVE WORK. 



Since the gipsy moth and brown-tail moth work was started by 

 the Bureau of Entomology more or less cooperative work has been 

 carried on with the States concerned. The introduction of para- 

 sites and natural enemies of the gipsy moth was conducted coopera- 

 tively with the State of Massachusetts for several years. After the 

 infestation covered large areas in other States an arrangement was 

 made for this work to be carried on by the Bureau of Entomology. 

 The general plan of field work is for the bureau to handle the terri- 

 tory embracing several tiers of towns along the outside border of 

 gipsy-moth infestation, while the States manage the work inside this 

 area. The quarantine covers the entire infested area, while the 

 experimental work, including the colonization of parasites, is being 



