OF WASHINGTON. 343 



ing the pine regions. Most of the coleopterous enemies of the 

 Scolytidse in Arizona are totally different from such forms in the 

 eastern United States. 



Dr. Hopkins, by invitation of the chair, presented some notes 

 on Scolytidae, with especial reference to habits. He showed the 

 male of Hypothenemus, which is relatively of extremely small 

 size, and is rare. H. dissimilis breeds in dead twigs, where the 

 larvae appear to consume a kind of ambrosia. In the first lot of 

 eggs deposited only one is a male, and this apparently is the only 

 male in the number of successive broods developed as a product 

 of a single female. There is, therefore, intense polygamy and in- 

 and-in breeding. Further notes were given on the habits of Cnes- 

 inus strigicolUs breeding in apple twigs, also on Pityophthorus 

 minutissimus, and Scolytus rugulosus, showing that the larva? 

 of Scolytids are sometimes killed by not very severe freezing, 

 from which he considered that the remarkable disappearance of 

 Dendroctonus frontalis in 1893 was due to the severe freeze of 

 December, 1892, and January, 1893. He mentioned a stridu- 

 lating sound made by Dendroctonus terebrans by rubbing the 

 dorsal margin of the last abdominal segment against the inner 

 surface of the elytra near the tips. The sound is apparently pro 

 duced by a vertical movement of the abdomen, which causes the 

 rubbing together of finely striated surfaces between the overlap 

 ping posterior sutures of the propygidium and the antepenultimate 

 segment, also of the sutures of the third and fourth segments from 

 the tip. He recorded the finding of Dendroctonus simplex 

 breeding in the American larch, in West Virginia, at an elevation 

 of 2,600 feet, and concludes that D. simplex may yet prove to 

 be distinct from D. rufipennls. He further presented some in 

 teresting notes on the insect enemies of Scolytidaa. 



This communication was discussed by Messrs. Schwarz, How 

 ard, Ashmead, and Johnson. 



Mr. Ashmead stated that all of the European parasites of 

 Scolytus rugulosiis have now been found in the United States, 

 the first one, Chiropachys colon, having been recognized 20 years 

 ago by Dr. Howard. 



Mr. Johnson stated that he had studied Scolytus rugulosus 

 in the orchards of Maryland during the past few years. He found 

 that it attacked plums and peaches with great virulence, but he 



