1920] ECONOMIC ZOOLOGY — ENTOMOLOGY. 255 



for the former and between 120 and 131° for the latter (in the adult condition). 

 An exposure to a temperature of 145.5° for five minutes is sufficient to kill 

 the larvje of C. oryza, and probably to sterilize the wheat completely as regards 

 all insect life. 



"Although a moist atmosphere is undoubtedly more favorable than a dry 

 one for the two weevils, both species can live and multiply in a dry in- 

 cubator, C. oryza increasing much more rapidly than (7. granaria provided the 

 Initial moisture content of the grain is sufficiently high. Very dry wheat is 

 less liable to attack by weevils than wheat with a moderate or high moisture 

 content, but wheat readily absorbs moisture in a damp atmosphere and thereby 

 becomes much more susceptible to weeviling. Rhizopertha can withstand dry 

 conditiims better than either of the two weevils. 



"C. oryza and C. yranaria are both likely to be serious pests in this country, 

 but little is to be feared from R. dominica under ordinary temperature con- 

 ditions. In addit)(m to the damage done by actual consumption of the grain 

 the presence of weevils results in extensive fouling with fecal matter, encourag- 

 ing the absorption of moisture and the ultimate rotting of the whole mass. 

 In large quantities of w-heat the process of decay is doubtless accelerated by 

 rise of temperature due partly to the presence of insects and partly to ' heat- 

 ing' of the wheat." 



Dusting V. spraying for the control of avocado insect pests, G. F. Moz- 

 NtTTK (Fla. Groiccr, 21 {1920), No. I4. pp. 8, 11, figs. 2). — The insects mentioned 

 as of particular importance as enemies of the avocado in southern Florida are 

 the avocado red spider (Tctranychus yothcrsi McGregor), greenhouse thrips, 

 and a leaf-hopper (Empoasca minuenda Ball). 



"The dusting method with dry dusting sulphur in a finely divided form was 

 found to be equally effective in keeping avocado trees free from red spiders over 

 as long a period of time as the spraying method with liquid lime-sulphur solu- 

 tion. The experiments proved that it is not necessary that the foliage of the 

 avocado be covered with dew, as the dry sulphur adhered to the foliage over a 

 considerable length of time. 



" Sulphur in any of the combinations used did not control leaf thrip or leaf- 

 hoppers, and nicotin sulphate as blackleaf 40 when combined with either lime- 

 sulphur or dry dusting sulphur will destroy them. Dry dusting sulphur when 

 charged with nicotin sulphate in the form of blackleaf 40 and applied to avocado 

 foliage was readily removed by succeeding heavy dews and light rains after 

 application. Apparently the liquid nicotin sulphate cau.sed aggregation of the 

 pulverized sulphur particles. Liquid lime-sulphur solution when combined with 

 blackleaf 40 proved to be the most satisfactory combination used in combating 

 the red spiders, leaf thrips, and leaf-hoppers, and remained effective against 

 the red spiders as long as did the lime-sulphur solution applied alone. 



" Where a grower has a medium-sized grove of avocados, which is usually 

 the prevalent case up to the present time, and where a number of insects occur, 

 spraying would be the more effective and cheaper method con.sidering the price 

 of sulphur and nicotin sulphate in the dust form compared with contact insecti- 

 cides in the liquid form." 



Important dried fruit insects in California, E. O. Essig {Mo. Bui. Dept. 

 Afir. (V/U 9 {1!)20), No. S, Sup., pp. 119-125, figs. 5).— A brief account of the 

 more important dried fruit insects and means for their control, particularly the 

 Indian meal moth, the fig moth {Ephcttia cauicUa Walk.), the dried fruit beetle 

 iC'nrixijihilus hrwiptrrus Linn.), and the saw-toothed grain beetle (Silvanus 

 Buriu(imrn.'<is L. ). 



187890°— 20 5 



