BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 25 
The large increase in numbers of Si s collected in 
1938 may be attributed to a marked increase in the available breeding 
material in the field. The amount of such material has been much 
reduced in 1939. and it is hoped that further increase in the beetle 
population will be checked. It will also be noted that there was an 
appreciable increase in the percentage oi both species of beetles carry- 
ing the fungus in 1938 over that in 1937. 
Laboratory and field studies have revealed thai adults of Ilybircjo- 
pkms rufipes frequently bore through the bark of living elm trees 
and contact the xylem. Much of this activity apparently takes place 
early in the spring before the spring ves the elms are mature 
and when chances of inoculation likely to occur. This partly 
explains why //. rufipes is less important as a carrier of the fungus 
than Scolytus m us. 
Water solutions of sodium arsenite. copper sulfate, ammonium bi- 
fluoride, copper nitrate, and copper chloride have been found effective 
in killing elm trees. When these solutions were injected into living 
trees in a foliar condition, they were effective in controlling attack by 
Scolytm m ultistriatus and Hyhirff&pk < us ruftyh s. Copper sulfate solu- 
tion has been used more than the other chemicals mentioned, and this 
at 60 grams per inch diameter (based on dry weight of the salt) on 
trees up to 12 inches in diameter at breast height. 
Preliminary studies have indicated that a combination spray of lead 
arsenate and lime-sulfur when sprayed on elms in foliar condition is 
effective in repelling Scolytus madtistriastus from feeding in the 
crotches. Some measure of success has been secured in killing bark 
beetle broods in elm logs by spraying the logs with fuel oil plus ortho- 
dichlorobenzene and fuel oil plus naphthalene. 
GYPSY AND BROWN-TAIL MOTH CONTROL 
Late in September 1938 the Xew England area, which is heavily 
infested with the gypsy moth, was visited by one of the most severe 
hurricanes in its history. This climatic disturbance resulted in dis- 
lodging many egn clusters of the gypsy moth, and it is possible that 
large numbers of them were carried, in whole or in part, by the tre- 
mendous force of the wind to territory heretofore uninfested by this 
insect. (The same may be true in connection with distribution, for 
short distance- at least, of brown-tail moth webs that had already been 
spun at the tips of the trees in the infested area.) The wind-blown 
trees afforded gene ral protection for the insect during the winter, and 
the snow cover was ample to provide protection in latitudes where ex- 
tremely low temperatures prevailed. 
This ground condition impeded the progress of scouting and clean-up 
work for control of this pest and added materially to its cost. For- 
tunately the acreage where trees were blown down in the barrier zone 
was confined to limited areas, but the territory east of it. particularly in 
the Connecticut River Valley and on toward the si 
suffered the greatest damage but furnished conditions favorab] 
continued infestation. 
J.iout th- year effective co* i has been maintained 
wiili the State ofl I by the 
Forest Service, and the Government officials <>l Canada in dealing 
