426 



by enforcing a migration in search of new food-plants. The adults 

 of Mayetiola destrvctor, the Hessian fly, suffer great mortahty when 

 forced to migrate through the introduction of an immune crop. Insects 

 having a wide range of food-plants are less affected. A constant supply 

 of wireworms, meadow maggots, click-beetles, cutworms, etc., emanates 

 from unbroken grasslands. A frequent breaking up of such lands in 

 the autumn, previous to changing the crop, will have a beneficial effect 

 in decreasing the numbers of field pests in general. In the case of such 

 forms as white grubs {Lachnosterna) and wireworms, it is important 

 that maize should be followed by a different kind of crop, since the 

 insects recjuire 2 or 3 years in the soil to complete their development. 

 The danger to maize from Sphenophorus parvuhis may be eliminated 

 by ploughing in autumn. The insects will abandon the field either in 

 autumn or in the following spring, in order to find timothy plants upon 

 which to oviposit. Early autumn ploughing is useful to destroy the 

 pupae of wireworms, white grubs and meadow maggots. Later 

 cultivation is effective in the control of grasshoppers, blister-beetles, 

 webworms and Aphis maidi-radicis. Special cultivation with the 

 spike-tooth disk-harrow is necessary to break up the egg-masses of 

 grasshoppers in lucerne fields. Clean cultivation will help to eliminate 

 such pests as aphids and cutworms. Modification of the time of 

 sowing constitutes a control measure of great importance. This is 

 especially the case with Mayetiola destructor, the fall army-worm 

 (Lajohygma frugiperda), and the corn-ear worm (Chloridea ohsoleta). 

 Maize planted on May 1st shows a yield of over 40 per cent, 

 more than that planted a month later, owing to the fact that 

 the silking period avoids the period of flight of the corn-ear moths. 

 The adjustment of the blooming period of certain leguminous 

 crops to protect them from attack by Bruchophagus funehris is 

 comparable with the adjustment of the time of seeding with 

 the cereal crops. Burning over grass land in late autumn 

 and early winter is the most eff'ective means of combating the 

 chinch bug, Blissus leucopterus. Wheat stubble should be destroyed 

 as soon as possible after harvest either by burning or ploughing ; in 

 this w^ay the pupae of the Hessian fly and the wheat straw-worm 

 will be removed. Treatment of maize seed with a mixture of oil of 

 lemon and wood alcohol prevents attack by brown ants and lice ; 

 soaking the seeds in Paris green and water and then thoroughly 

 drying is said to repel corn-seed beetles. Aphis maidi-radicis can be 

 controlled by adding oil of tansy to any fertiliser in the proportion of 

 1 lb. in 1 gal. wood-alcohol to 100 lb. fertihser. The use of poisoned 

 bran mash has given good results against grasshoppers, cutworms and 

 click-beetles. Barriers, in the form of furrows or lines of coal tar or 

 road oil, prevent the migration of army worms, cutworms and chinch 

 bugs. Feeding pigs in fields infested with white grubs, meadow 

 maggots or cutworms has been found a most effective way of destroying 

 these pests. 



Oberthur (C). Etudes de L6pidopt6rologie compar^e. [A Compara- 

 tive Study of the Lepidoptera.]— i?e>i«€5, x, March 1915, pp. 459, 

 42 figs. 

 This volume contains an account of the Lepidopterous fauna of 



Barbary. a few of the species described being of economic interest. 



