SIXTH REPORT OF THE DIRECTOR I909 5 1 



fered greatly in recent years from outbreaks by leaf-feeding 

 caterpillars. The snow-white linden moth has been one of the 

 chief offenders. The past season was marked by extensive 

 depredations by this pest. The flight of hosts of white moths 

 about city and village lights, so generally noticed in 1908 was 

 observed the past season. 



The small, modest, grayish and olive-brown moths of the 

 spruce bud Avorm attracted unusual notice in midsummer on 

 account of their prevalence at street lights in a number of 

 widely separated cities. These flights, judging from reports re- 

 ceived, have been preceded by serious injuries to spruce trees in 

 the Adirondacks. 



The hickory bark borer, a most pernicious enemy of hick- 

 ories, has been very injurio'j.s to the magnificent trees of Pros- 

 pect Park, Brooklyn. Injuries by this pest have also been re- 

 ported from the central portion of the State. This nefarious 

 insect has m recent years destroyed thousands of valuable trees 

 in this State. Its potentialities for evil amply justify the prompt 

 destruction of infested trees. 



Gipsy and brown tail moths. The appearance of the latter 

 species in this State has already been mentioned and must be 

 regarded as but the precursor of similar visitations. This in- 

 sect has not, to our knowledge, become established west of the 

 Connecticut valley, and it is to be hoped that the repressive 

 measures, prosecuted jointly by the State of Massachusetts and 

 the federal government will result in keeping this destructive 

 form at a distance for some years to come. 



The finding of numerous winter nests of the brown tail moth 

 upon imported French stock last winter resulted in our con- 

 ducting a series of experiments for the purpose of determining 

 the efficiency of hydrocyanic acid gas as an agent in the destruction 

 of the caterpillars. Though this most deadly gas has given ex- 

 cellent results with other species, it proved of no service in 

 killing brown tail moth caterpillars within their nests, and 

 could not be relied upon to destroy free caterpillars in a dor- 

 mant condition at any reasonable strength and without an un- 

 duly prolonged exposure. The details of these experiments, 

 showing the unreliability of this gas, are given in the full report of 

 the Entomologist. On the other hand, dipping the caterpillars in a 

 miscible oil placed upon the market under the commercial name of 

 scalecide, was invariably followed by death. 



