26 



Gibson (A.). The Value of High Temperature for Controlling the 

 Common Bedbug. — Agric. Gaz. Canada, Ottawa, v, no. 10, October 

 1918, pp. 949-951, 2 figs. 



During the summer of 1918 a four-roomed cottage at Ottawa, 

 which was badlv infested with bed-bugs, was successfully treated by 

 superheating. 



The windows having been made air-tight, heat was suppHed by two 

 plasterer's stoves. On the day on which the experiment was made, 

 the outside temperature at 4 p.m. was 60-4° F. The fires were started 

 at noon, high temperatures (120°, 115°, 165° and 140°) being reached 

 in all the rooms by 4 p.m. At 8.30 p.m. the fires were checked, but 

 not put out and the temperatures continued high for at least an hour 

 after that time. At 6.30 p.m. a thorough examination of the premises 

 showed absolutely no sign of life, a large number of dead bugs being 

 found lying on the bedroom floors. This result confirms previous 

 experimental work as to the effect of heat on bed-bugs. 



Sen (S. K.). Beginnings in Insect Physiology and their Economic 

 Significance. — Agric. Jl. India, Pusa, xiii, no. 4, October 1918, 

 pp. 620-627. 



Investigations on mosquito larvae with regard to osmosis have 

 shown that equi-molecular solutions of cane-sugar and common salt 

 act differently on them. Thus 12 larvae in 15 c.c. water containing 

 3 gm. sugar all died in from 9 to 22 hours ; 12 larvae in 15 c.c. water 

 containing | gm. salt (sea- water strength) all died in about 3 hours ; 

 while in a mixture of equal parts of the above solutions they were 

 mostly dead in 9 hours. 



As regards the respiration of mosquitos, experiments have shown 

 that larvae and pupae enclosed mth a known quantity of air consume 

 the whole amount of the oxygen present before dying, thus indicating 

 the thoroughness with which remedial operations on the principle of 

 deprivation of free air must be carried out. 



Little is known of the nature of the digestive secretions of insects, 

 but the fact that mosquito larvae thrive on Sanatogen, a glycero- 

 phosphate of casein, suggests that protein is necessary for their tissue 

 formation. However, on the other hand, it may be that they thrive 

 at the expense of bacteria present as the result of putrefaction due 

 to the introduction of Sanatogen. The fact that the protein require- 

 ments of some insects is practically nil is proved by their being able 

 to live on a solution of simple carbohydrate, such as cane-sugar. The 

 liking shown by many insects, such as mosquitos, for sugar makes 

 it difficult to vmderstand why these insects should exhibit a liking for 

 two such dissimilar substances as blood and sugar, the percentage of 

 dextrose in blood being too small to impart a sweet taste, especially 

 in the presence of so many inorganic salts. Experiments have estab- 

 lished the following conclusions : — (1) Warmth, though it actuates the 

 mosquito to bite, does not encourage it to suck ; (2) the salinity of 

 blood is not what induces it to suck ; (3) sugar in blood is not what 

 induces it to suck ; (4) shed goat's blood is not attractive to 

 mosquitos. 



The hypothesis that blood is necessary for ovulation in mosquitos 

 is contradicted by the fact that freshly emerged females of Stegomyia 



