144 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 6 



large tracheal trunks, air sacks, etc., mechanical ventilation, accomplished 

 by body movements, supplements gas diffusion. But even in these forms 

 gas exchange in the finer tracheal branches must be accomplished by diffusion. 

 The Dytiscus larva is a type which shows both mechanical ventilation and 

 gas diffusion. 



Mr. E. R. Sasscer discussed Mr. Richardson's note in its relation to dis- 

 infection with poisonous gases. In reply to questions he stated there is 30% 

 more gas in sodium cyanide than in potassium cyanide, and that dormant 

 insects are more resistant to gas poisoning than active insects. 



Mr. Wm. MiddlETOn presented Some notes on the terminal abdominal 

 appendages of saw-flics, taken from a paper bearing the above title, which 

 will be published elsewhere. 



Mr. H. K. Plank exhibited adult specimens of a new pest of the cranberry, 

 the cranberry root weevil, Geoderces incomptus Horn, from near Cranberry 

 Station, Washington, and showed photographs from life of the eggs, larvae,, 

 pupa, and adult, also of the female in the act of ovipositing in folds of a "buck 

 brush" leaf. Spiraea douglasii, sl common bog plant. He described briefly 

 the work o the larvae and adults, showing photographs of larvae feeding on 

 the small roots of the cranberry just beneath the surface of the bog, the de- 

 structiveness of the larvae, and the adults in the act of feeding on the terminal 

 leaves of the cranberry upright. 



Mr. Plank also exhibited specimens from Seaview, Washington, of a species 

 of Spicaria, a new fungous disease of the pupae of the blackhead fireworm, 

 Rhopobota naevana Hn. The identification of this insect was made by Carl 

 Heinrich of the U. vS. National Museum. It is the same species that occurs 

 on the bogs of the east and in Europe, of which vacciniana Pack, is a synonym. 

 This fungous disease attacks the pupa in its loosely constructed cocoon in 

 the trash and leaves beneath the vines and becomes apparent about early or 

 mid August. 



Mr. Plank called attention to the single generation of Rhopobota naevana 

 Hn. on one bog near Cranberry Station, Washington, as compared with two 

 and three generations of the same species on other bogs in the same general 

 locality. The range of the daily temperature on the former is somewhat 

 greater, and this bog is also somewhat more wind-swept than the bogs on 

 which two and three generations exist. Specimens of adults were exhibited. 



Mr. L. O. Jackson told of an encounter observed by his mother between 

 a bumble bee and a white-faced hornet {Vespa maculata), in which the bumble 

 bee came off victorious. 



A note on Hymenoptera at the British Museum by T. D. A. CockerELL was 

 read by Mr. RohwER, as follows: 



"When I visited the British Museum about 15 years ago, I found Col. Bing- 

 ham arranging the ants, but the bees had never been rearranged since the 

 death of F. Smith about 26 years before. The progress made since 190.5 is 

 remarkable, and it will be of interest to quote a summary from a recent 

 (Nov. 26, 1919) letter received from Mr. Rowland E. Turner: 



' ' 'Meade-Waldo had practically finished the bees before his death, including 

 the incorporation of the Biologia material except the Prosopis group. They 

 now occupy 12 cabinets; Diplotera 4, Sphegidae 7, Psammocharidae 6, Mutil- 

 lidae, Thynnidae, and Scoliidae 6; so that Aculeates are pretty well incorpor- 

 ated up to date excepting ants and Mutillidae. I have recently got the 



