425 



of arsenic, such as lead arsenate, Paris green, calcium arsenate, and 

 others, have particles carrying negative electric charges. Arsenic 

 compounds of aluminium, chromium, and iron may be prepared so 

 that the particles carry a positive charge. Ferric arsenate appears 

 the most promising and is more toxic than lead arsenate. Field 

 tests show that electrically positive arsenical preparations adhere 

 more strongly to the leaf surface than do those that are negatively 

 charged. Ferric oxide or hydroxide, by adsorbing compounds of 

 arsenate, lower their toxicity to insects. The ratio of the amount 

 of the arsenic compound in the body to that in the excreta is a better 

 basis of comparing the toxicity of different arsenical preparations 

 than tests based on the food consumed or the time required to produce 

 death. 



O'Kane (W. C.) & Osgood (W. A.). Studies in Termite Control.— 



New Hampshire Agric. Expt. Sta., Durham, Bull. 204, April 

 1922, 20 pp., 1 plate, 5 figs. 



The following is a portion of the authors' summary : — 

 The infestation here described took place in a modern hospital in 

 a New Hampshire city and involved extensive damage to partitions, 

 floors, beams and other woodwork. A large amount of infested material 

 was removed and destroyed. Tiles and cement were substituted. 

 Preliminary experiments were arranged to determine the time and 

 temperature factors necessary to kill termites in wooden beams by 

 heat. Supplementary steam piping was installed in the basement, 

 and the temperature was raised to 135° F. for 24 hours. No living 

 termites have since been discovered within the building. The structure 

 remained in undisturbed use for hospital purposes while the heat, 

 treatment was going on. Extensive infestation was found through 

 much of the hospital grounds. Board traps were utilised to discover 

 the extent of this infestation. Timbers, board walks, apple trees, 

 etc., were removed. A mixture of Phinotas oil and water at a dilution 

 of \ per cent, was used to kill termites in the ground and to render 

 the ground unacceptable to them. .??| 



Bodkin (G. E.). The Scale Insects o£ British Guiana.—//. Bd. Agric. 

 Brit. Guiana, Georgetown, xv, no. 2, April 1922, pp. 56-63. 



Ninety-four species of scale-insects are recorded from British Guiana, 

 and notes on those collected in 1914 are given [cf. R.A.E., A, ii, 

 416, etc.]. 



Hegh (E.). Les Termites. — Bull. Agric. Congo Beige, Brussels, 

 xih, no. 1, March 1922, pp. 91-204, 70 figs. [Received 22nd 

 June 1922.] 



In this instalment of his monograph on African termites [R.A.E., 

 A, X, 284] the author deals particularly with the construction of the 

 nests. 



The distribution of termites in Australasia is discussed in an appendix, 

 and a list is given of 80 species known to occur there up to 1919. 



MiEGE (E.). Sur deux Insectes parasites au Maroc : Tephroclystia 

 puniilata et Plusia chalcytes. — Bull. Soc. Path. Veg. France, Paris, 

 ix, no. 1, January-March 1922, pp. 52-54. 



The Geometrid, Tephroclystia puniilata, is recorded as a pest of 

 maize in Morocco. The eggs are laid on the stigmata of the female 



(6974) 2 F 



