336 WEST VIRGINIA EXPERIMENT STATION 



FURTHER OBSERVATIONS ON NATURAL ENEMIES. 



Some more examples of the predaceous Clerid ( Thanasimus 

 dubius} were found, but not common enough to be rendering 

 much apparent service in reducing the numbers of the bark 

 beetle. The rapid increase of this beneficial insect was probably 

 prevented by two parasites, one which 1 was bred from an adult 

 collected at the time and another 2 subsequently bred from the 

 larva. Other enemies of the bark beetle were found at this 

 time, and still others had been previously observed, but none 

 of them alone, or all combined, appeared to accomplish much 

 towards checking the trouble. 



Two adults of the Clerid ( Thanasimus dubius) taken at this 

 time were placed together in a bottle where it was found that 

 they would vigorously attack each other and had to be separ- 

 ated to prevent both from being killed. I subsequently found 

 that if one succeeded in killing the other, it would, if not ser- 

 iously hurt, deliberately proceed to devour its victim. The 

 same was found to be true with the larvae. This fact suggested 

 the necessity (if members of the family Cleridae were to be 

 imported from Europe) of placing each individual in a separate 

 receptacle, and I found that small, glass vials just large enough 

 to accommodate a single specimen, suited the purpose admir- 

 ably. I also discovered that one adult Clerid when confined in 

 a bottle, would readily attack and devour any species of bark 

 beetle placed with it. The knowledge of these facts with re- 

 ference to the habits of this American Clerid, proved to be ex- 

 ceedingly valuable to me in my investigations in Europe. 



DYING SPRUCE AND PINE IN MARYLAND AND DISTRICT OF COLUMBIA. 



On my way to New York on Aug. 10th, I observed from the 

 car windows on the B. & O. R. R., large areas of dead and dy- 

 ing pines on the mountains in Maryland and West Virginia, 

 the trouble having spread at an enormous rate since the pre- 

 vious May, Upon my return from Europe I observed, as pre- 

 viously noted, that the trouble had extended as far east as 



1. Tachina sp. 



2. Ichneumonid (t) 



