1918.1 ECONOMIC ZOOLOGY ENTOMOLOGY. 859 



of three important leaf-hoppers attacking apple, Empoasca mali, E. unicoloi; 

 and Empoa roscc. 



During the summer and fall of 1915 there was a heavy infestation in the 

 district of western New York about Geneva of E. mali and E. rosce was quite 

 common. Their attacks were in evidence in all orchards observed, whereas 

 E. unicolor was comparatively rare and no cases of heavy infestation were 

 observed. During the following season, which was fully two weeks later than 

 normal, E. mali, though decidedly injurious, was less in evidence than during 

 the preceding season, while E. unicolor was exceedingly plentiful, proving to 

 be a true pest and by far outnumbering E. mali. E. rosw was again prevalent 

 in 1916, and in spite of its natural enemies did considera-ble injury. 



On apple E. mali feeds almost exclusively on the tender terminal growth and 

 shows a marked preference for young, growing trees. E. rosw and E. unicolor 

 both largely attack the older leaves, but occur on both old and young trees. 

 E. mali causes a severe and characteristic curling of the foliage and resultant 

 injury to the trees. Further experiments must be conducted before any conclu- 

 sion can be drawn as to their transmission of fire blight. 



E. rosoi and E. unicolor pass the winter in the egg stage, while E. mali hiber- 

 nates largely if not exclusively in the adult stage. 



A graph is given showing the life cycles of the three species as observed at 

 Geneva during the two seasons. 



Texas aphid notes, F. B. Paddock (Jour. Econ. Ent., 11 {1918), No. 1, pp. 

 29-32). — A brief review of observations of plant lice in Texas that have been 

 recorded by the author and others. 



A simple means of ascertaining if a sterilizing hut is hot enough to de- 

 stroy lice and nits in clothing- or blankets, A. Bacot {Brit. Med. Jour., No. 

 2953 {1917), p. 151).— The author has found that stearin, which melts at 60° 

 C. (140° F.), is a satisfactory indicator as to tlie amount of heat and length of 

 time required for destroying lice and nits in clothing and blankets, nits pro- 

 tected by a single thickness of khaki cloth being killed by 15 minutes' exposure 

 to a temperature of 52°. Seven gm. of stearin in a porcelain pot 2.5 in. deep 

 and 2.5 in. in diameter requires 30 minutes to melt, a small portion being still 

 unmelted after 25 minutes ; 10 gm. requires between 40 and 50 minutes for melt- 

 ing, only a narrow ring being melted within 30 minutes. 



" If two pots, one containing 7 gm. and the other containing 10 gm., are 

 placed or hung slightly below the level of the lowest garments in the sterilizing 

 room, one can be sure, if all the stearin in the 7 gm. pot is melted before the 

 removal of the garments, that the exposure has been sufficient, botli as regards 

 period and heat ; while, if all the stearin is melted in the pot containing 10 gm., 

 it will show that greater heat or longer exposure than was necessary has been 

 used. ... 



" Nits and stearin were exposed together, and it was found that the stearin 

 was more resistant to these conditions than the nits. For instance, when the 

 temperature was rapidly raised from 21 to 80° within 20 minutes, the nits were 

 killed, while the 7 gm. of stearin was not quite all melted. A rise to the same 

 temperature in IS minutes showed the same result. A rise to 82° in 15 minutes 

 was jxist sufficient to melt aU the stearin, the nits being kiUed. Again, a rise 

 in 12 minutes to 81° killed the nits, but left a central disk of stearin unmelted." 



Annual reports of the Royal Sericultural Station, Padua, E. Verson et at.. 

 {Ann. R. Staz. Bacol. Padova, 89-40 {1911), pp. 282, pi 1, figs. S; 41 {1914), 

 pp. 201; pU. 4; 42 {1915-16), pp. 185, pl-s. 3, figs. 13).— These ai-e the usual re- 

 ports (E. S. R., 25, p. 662) dealing with sericultural investigations. Each 

 includes a list of publications relating to the subject that were issued during 

 the period covered. 



