36 NEW YORK STATE MUSEUM 



sects. Such is very likely to be followed by attacks upon trees 

 which, under normal conditions, would escape unharmed. Causes 

 such as those just mentioned are rare in the less thickly wooded and 

 more settled sections where extended, close stands of timber and 

 extensive logging operations are almost unknown. It is in just 

 such regions as these that severe droughts are most prevalent 

 and injurious, and in such localities it seems very probable that 

 a great scarcity of moisture for an extended period may be an 

 important primary cause in inducing serious injury by bark borers. 



PITTED AMBROSIA BEETLE 

 Corthylus punctatissimus Zimm. 



The work of the pitted ambrosia beetle is indicated by wilting 

 or dead shoots easily broken off near the surface of the ground and 

 revealing a series of blackened, closely set, nearly horizontal gal- 

 leries some one-sixteenth of an inch in diameter and frequently 

 containing, especially in the vertical brood chambers, stout, cylindric, 

 black' beetles about one-eighth of an inch long. This borer, work- 

 ing, as it does, at the base of the shoots, weakens the entire stem, 

 while the rhododendron clear-wing, noticed elsewhere in this re- 

 port, may limit its injuries to portions of a shoot and its galleries 

 are rarely within a foot of the ground. The hybrid rhododendrons 

 appear to be exempt from attack. 



Injuries. An examination September 24th of conditions on the 

 estate of Mr C. H. Matthiessen, Irvington, N. Y., showed that 

 portions of rhododendron beds 50 to 150 feet in length which, it 

 was stated, had earlier been in a thriving condition, and standing 

 from 3 to 5 feet high were then in a very unsatisfactory condition. 

 Few of the shoots were over 2 feet in height, there were open 

 places here and there and sickly or wilting shoots were plainly in 

 evidence. Mr Matthiessen stated that this trouble has been apparent 

 upon his place for several years and that, in his opinion, much of 

 the injury due to this beetle had been blamed by growers, upon 

 drought and other untoward conditions. The stems attacked varied 

 in diameter from approximately half an inch to an inch or an inch 

 and one-fourth. Specimens received from Mr Charles Goodyear, 

 Rockwood, Tarrytown, showed that this borer is also at work there, 

 though examinations of rhododendrons in the New York Zoological 

 Garden and in Prospect Park, Brooklyn, have failed to reveal the 

 presence of this beetle. 



There is an extremely interesting record of injury by this species 



