1"20] ECONOMIC ZOOLOGY — ENTOMOLOGY. 253 



simpler S;i.v), tlio larva of wliicli attacks tlio rico roots and is ooiiinionly knowTi 

 as tht> " iiia.uirot " is (lie iiicst important. A import of stndies of tills pest l)y 

 Tucker lias iiecn previously noted (E. S. 11., 27, p. 5G2). 



The peiitatoiiiid bu;; Oebnlus pugnnx Fab., may reduce the yield, its attack lie- 

 inj; confined to late summer and early full when the rice heads are forming, the 

 mature and nearly mature bufis attacking; the soft j?rains of rice. It is tliou^dit 

 that a considerable amount of the injury and lo.ss caused by it can be avoided by 

 Retting the crop in early in the spring. 



The fall army worm occasionally becomes abundant in the rice tields in the 

 spring before the rice is flooded, and unless prompt measures are taken it soon 

 works great havoc. It is easily controlled, however, by flooding the fields and 

 drowning out the worms. 



The rice stalk-borer {Chilo plejodcUus Zincken) is mentioned as occasionally 

 causing injury, the feeding of the larva (m the inner stalk causing the head to 

 die before maturity. Several other insects are also mentioned as at times injur- 

 ing the rice crop, including the southern corn rootworm, which attacks the rice 

 seed after it is planted, completely destroying its power to produce a plant, 

 and the rough-headed corn stalk-borer [{Liyyriis) Eucthcola rugiccps Lee] 

 which attacks the main stem of the rice plant just above the roots, shredding 

 it and causing the plant to die. 



The best nrethod of controlling in.sects in rice fields is summarized by the 

 author as follows: "Plow fields in fall previous to planting time to kill ]»ests 

 in the soil. In the case of sod land, cultivate thoroughly in the fall. If fall 

 plowing Is not done, burn off all vegetation during winter to desti'oy pests over- 

 wintering in the dead gra.ss and weeds. Three weeks after first flooding, drain 

 fields for two weeks to prevent damage by root maggots. In case of caterpillar 

 or worm attack upon the leaves, flood the field immediately. Keep down all 

 weed growth around the field and on the levees separating the plats. This will 

 greatly reduce attack by many minor species of insects which normally breed in 

 these weeds. 



Wheat and its pests, H. R. Rathbone (Roy. Soc. [London], Grain Pc.sts 

 (liar) Com. Memo. 6 {J919), pp. 4)- — This is a brief summary of inforiiiation on 

 the more important enemies of wheat. The weevils, which are the most de- 

 structive and troublesome, are Rhizopcrtha domniica, the granary weevil, and 

 the rice weevil. The first is very destructive and troublesome and at times it 

 flies in millions; the second does the most damage, but being unable to fly is 

 more easily controlled than the rice weevil. Many million bushels of wheat 

 have been destroyed by these in.sects in Australia. 



Report on the effect of air-tight storage upon grain insects, III, A. 

 I)KNi)Y and 11. I). Ei.KiNGTON (Rpts. Grain Pest.s (War) Com., Roy. Soc. [Lon- 

 don], \o. 6 (J'J20), pp. 51, fig. 1). — This third part of the work previously noted 

 (E. S. R., 40, p. 8.55) has been summarized by the authors as follows: 



" Grain insects sealed up in air-tight vessels, with or without wheat, suc- 

 cumb as .soon as the oxygen has been used up, a corresponding amount of car- 

 bon dioxid being producetl. The only gases present in such sealeil vessels, urider 

 normal conditions, are oxygen, nitrogen, and carbon dioxid. The amount of 

 carbon dioxid given off by live wheat in air-tight vessels varies directly with 

 the moisture content and the temperature. As regards moisture content there 

 Is a critical point, above which tlie production of carbon dioxid by wheat sud- 

 denly increases very greatly. This critical point varies with the temperature. 

 For the temperature and wheats investigated it lies between 13.25 and 10.95 

 per cent. Above the critical point of moisture content wheat stored in air- 

 tight receptacles very soon renders itself immune to the attacks of grain in- 



