374 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



Eccoptogasler quadrispinosa Say, has swept out of existence thousands 

 of hickories. It is well known that comparatively minor factors may 

 turn the balance in favor of or against a destructive insect, and in 

 connection with the above mentioned depredations we have looked 

 for some general cause. 



The outbreak by the hickory bark beetle in New York City and 

 vicinit}' began about 1908, and an examination of the weather bureau 

 records of that locality show an interesting condition. From 1906 

 to 1912 inclusive, there has been a deficient rainfall, except for 1907, 

 at which time there was an excess of only half an inch. The total 

 deficiency during this period amounted to 28.56 inches. The most 

 marked deficiency for that period was in 1910, with a precipitation 

 8.75 inches below the normal, a reduction of approximately one-fifth. 

 A scrutiny of the monthly precipitation shows that in 1906 the scarcity 

 of rainfall occurred mosHy from June to September, there being during 

 these months from an inch to nearly an inch and a half less than the 

 normal. The next year, 1907, although there was a slight increase 

 in the annual rainfall, there was a considerable shortage for the months 

 of July and August, this amounting respectively, to 3.36 and 2.05 

 inches. In 1908 there was a shortage of 1.56, 1.99 and 1.79 inches 

 for the months of June, September and October, respectively. In 



1909 there was a scarcity of rain during May, June and Julj^ amount- 

 ing respectively, to 1.46, .09 and 2.56 inches, there being an excess in 

 August of 3.41 inches and a shortage in September of .93 inches. In 



1910 there was a shortage in July, August and September amounting 

 respectively, to 4.31, 2.40 and 2.16 inches with a slight excess in June 

 of 1.84 inches. In 1911 there was a deficient rainfall in May, July 

 and September amounting respectively, to 2.27, 2.99 and 2.08 inches, 

 while in 1912 the deficiency from June to September, inclusive, was 

 2.09, 1.28, 1.7G and .21 inches for the four months in the order named. 



Although the deficiency during this period was not as a whole very 

 excessive, it will be noted that it was progressive and that the shrink- 

 age in rainfall almost invariably cam.e during the growing months and 

 at times most likely to affect vegetation adversely. The general re- 

 sult in this region was abundantly evidenced by the unfavorable con- 

 dition of the trees throughout the section, this being particularly 

 marked in 1910 and 1911 and was accompanied by an abnormal scarc- 

 ity of water. A number of trees, particularly soft maples and others 

 standing in naturally moist, low localities, died, the major cause prob- 

 ably being scarcity of moisture. 



With the above facts in mind it seems reasonable to believe that 

 these unfavorable climatic conditions may have reacted upon the 

 trees, reducing their normal resistance considerabl}' and resulting in 



