38 



some velvet beans been raised in the greenhouse for them. The 

 abihty of A. gemrnatilis to reach so far north as Canada is to be 

 explained by its longevity. A brief description of the life-history 

 of the insect is given. In September it spends about 3 days in 

 the egg-stage and 21 in the larval, passing through 6 instars. The 

 pupal stage averages between 10 and 11 days in September. As the 

 weather became cooler this time was gradually lengthened. 



Rand (F. V.). Dissemination of Bacterial Wilt of Cucurbits. (Prelimi- 

 nary Note). — Jl. Agric. Research, Washington, D.C., v, no. 6, 

 8th November 1915, pp. 257-260, 1 plate. 



According to Dr. Erwin F. Smith, leaf-eating insects, especially 

 Diahrotica vittata, are the chief agents in the spread of the bacterial 

 wilt of Cucurbitaceous plants. It was suspected that the organism 

 might pass the winter inside the bodies of these hibernating insects. 

 In order to elucidate this point and to develop some practical method 

 of control, the author has further investigated this frequently 

 destructive disease and a number of cage experiments were made. 

 From these it would appear that the wilt bacteria are carried over the 

 winter by the hibernating beetles and inoculated into the cucumbers 

 as they feed upon the young leaves. Only those beetles which have 

 previously fed upon wilted plants convey the disease. 



WooDwoRTH (C. W.). The Efficiency of Spray Machinery. — California 

 Cultivator, Los Angeles, xlv, no. 19, 4th November 1915, p. 451, 

 1 table. 



This paper gives an account of the method of testing the efficiency 

 of spraying apparatus by a comparison of the theoretical horse- power 

 with that obtained in actual practice. The method of testing is to 

 find the maximum pressure the engine will exert with all the 

 lines of hose open and the time taken, under these conditions, to fill a 

 50 gallon barrel. By consulting the table, this result can be compared 

 with the theoretical power and thus the efficiency of the engine 

 may be determined. 



WooDWORTH (C. W.). Time of Fumigation. — California Citrograph, 

 Riverside, Cal., i, no. 1, October 1915, p. 8, 2 figs. 



The eggs of scale-insects were submitted to the action of cyanide gas 

 at varying strengths and for different periods of time. After treatment 

 the gas was allowed to escape from the enclosing capsules and the eggs 

 were left to hatch. The largest number of eggs which hatched had 

 been exposed longest to gas which was too dilute to kill. This stimu- 

 lative action of dilute gas does not become evident until after at least 

 an hour's treatment. In dealing with stronger gas, it has been found 

 that a double dose gives the same killing effect in approximately one- 

 tenth of the time. In field experiments, the difference in the leakage,, 

 which in an average-sized tree is compensated for by a change of 1 oz. 

 in the dose, could be equally well compensated for by a change of 40 

 per cent, in the time. For example, an 8 oz. dose for 45 minutes would 

 have the same killing power as a 7 oz. dose for 1 hour, or a 9 oz. dose 

 for 32 minutes. 



