172 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



Locations for screen experiments were selected with reference to dis- 

 tance from infested woodlands and nature of surrounding vegetation; 

 that is, finding areas where there was little favorable food for the 

 gipsy moth, so that little scouting had to be done to determine if the 

 eggs of the insect were already present. Marsh areas, beaches, and 

 islands off the coast best met these requirements. A screen was thus 

 located at Salisbury Beach and Plum Island, Mass., where large ex- 

 panses of salt marsh from one to two miles wide separated the infested 

 woodlands from the sandy beaches and ocean. 



An altitude experiment with aviation of small caterpillars was 

 conducted at Merrimac, Mass., which consisted of a screen 36 feet 

 long and 4 feet high erected on top of the town standpipe. The 

 latter was located on a hill and towered 55 feet above the summit, so 

 that the screen was 300 feet above sea level. Other hills one-half 

 mile and more distant, also the valleys were generally infested and 141 

 newly-hatched larvae were taken in a season on this screen of 144 square 

 feet. This experiment together with three large screens located on 

 hilltops in New Hampshire gave data which assisted in explaining 

 the source of many new infestations found during the scouting opera- 

 tions on hilltops in outside territory. 



A location for a screen on the Isles of Shoals, N. H., was selected on 

 Lunging Island, the most western of the group. These islands are 

 located six miles from the nearest mainland and 13| miles from mouth 

 of the Merrimack River to the southwest. Living gipsy moth larvae 

 were removed from the screen during a continuous period when 

 southwest winds were blowing, thus proving that they are wind borne 

 13| miles or farther. After securing a total of 67 newly hatched 

 gipsy moth larvae on the screen at Isles of Shoals in 1914, nine of which 

 were wind borne from a distance of 13§ miles or more, it was evident 

 that the maximum distance had not been found. A location was then 

 searched for where a screen could be erected an even greater distance 

 from infestations, and this was found on the end of Cape Cod, Province- 

 town, Mass. Here a large poultry wire screen was erected on the sand 

 about 75 feet from the shore and near Race Point Light. 



Tanglefoot was applied and examinations were begun at the dis- 

 persion period of 1915. Winds striking the screen at this point from 

 the south, southwest, west or northwest must pass over 19 to 35 miles 

 of salt water from the mainland. Two to three examinations of the 

 screen daily were made during the dispersion period in 1915. 



In order to further check these data on long distance spread, the 

 Provincetown screen which was razed during a storm in winter of 

 1915-16 was rebuilt in the spring of 1916. New wire of |-inch mesh 

 was applied, as the old tanglefoot so darkens after one year that it is 



