213 



of the coal-tar-neutral oil and 4 lb. slaked lime were then mixed and 

 stirred, and when of a uniform consistency, 20 lb. of resin oil w^as 

 added and stirred and then 10 lb. more of the coal-tar neutral oil ; 25 

 minutes after the addition of the resin, the stirring was stopped and 

 the material dumped into tubs ; after standing for two days it was 

 semi-solid and 2 lb. of the coal-tar neutral oil was stirred into each 

 50 lb. of this mixture in order to produce the desired oily surface. 

 This material is cheaper than any successful tree-banding material 

 previously made ; the bands can remain on the trees during the winter 

 and, if moistened with turpentine in the following spring, are effective 

 for two seasons. This material does not run under a high temperature, 

 nor harden after rain, but when used on dusty highways, requires 

 occasional attention. 



Ball (E. D.). Efficiency and Economy in Grasshopper Control. — 

 Jl. Econ. Entom., Concord, N.H., x, no. 1, February 1917, 

 pp. 135-138, 1 fig. 



The ideal control for grasshoppers is a combination of poison bait 

 along fences and ditches or on crops lilce tomatoes, beans and maize, 

 and the use of the grasshopper- catching machine on lucerne, sugar- 

 beet, timothy grass and grain before flowering time. These methods 

 have been dealt with in a previous paper by this author [see this 

 Review, Ser. A, iii, p. 466]. 



Phillips (W. J.). Report on Isosoma Investigations. — Jl. Econ. 

 Entom., Concord, N.H., x. no. 1, February 1917, pp. 139-146, 

 2 plates. 



Isosoma tritici is one of the most miportant pests of wheat in the 

 Eastern States, but has not yet been found in the great w^heat belt of 

 the west. The injury it does has often been confused with that done 

 by the Hessian fly [Mayetiola destructor']. There are 23 distinctly 

 recognisable species of Isosoma occurring throughout the United 

 States, 5 of which appear to be strictly western species, 12 strictly 

 eastern and 6 that overlap. A new type of gall recently observed is 

 apparently the work of a new and midescribed species of Isosoma, 

 the galls always occurring in the leaf-sheath surrounding the head, 

 and often showing a root-like growth at the base of the gall. These 

 insects were found very difficult to breed in captivity, but from 

 studies of individual species it seems certain that the three species 

 occurring in wheat caimot be induced to breed in any other plant, 

 and the same may be said for those species occurring in rye, barley, 

 etc. This is a fact of economic importance in considering control 

 measures. The eggs of /. tritici are laid between the fibrovascular 

 bundles of wheat stems and hatch in 10 days. The gall begins to 

 form before the hatching of the egg, disarranging the position of the 

 fibrovascular bundles and causing the stems to fall. The larvae 

 moult three or four times, and mature in about three weeks. 



All the twelve species studied were fomid to be parthenogenetic. 



Elymus is the most favoured host of Isosoma, seven species having 

 been reared from it ; wheat and Agropyron sp. are attacked by 

 three species ; rye and blue-grass {Poa 2)ratensis) by two ; and barley, 

 timothy {PJileum 'pratense), orchard grass {Dactylis glomerata), Poa 

 sp., Festuca sp. and Bromus sp. by one each. 



