391 



Many experiments were ina(l»> to ascertain, if possible, what sub- 

 stances could be economically introduced into the soil inf"sted with 

 white grubs which should destroy them, while not injuriously affecting 

 the crops. Although the results reached werc^ less definite and satis- 

 factory than were desired, it may be worth while to state some of them 

 as briefly as possible. Several of the larvie infested with Cordyceps 

 were placed in a box of sandy soil and such conditions preserved as 

 were thought favorable to the development of the fungus. Healthy 

 larvse were also placed in this box. The fungus did not develop spores 

 and the uninfested larvnB were not attacked during the time of the 

 experiment, but this may not have been sufiicient for the production 

 of the desired result. The accounts of Prillieux and Delacroix in 

 Compte Bendus, May 11, 1891, show that the European Melolontha can 

 be successfully attacked by a fungus, and culture tubes are offered 

 for sale. 



Freezing the earth even when the degree of cold was not below zero 

 F. destroyed all contained larva?. This is remarkable because, as has 

 been noticed, active and apparently healthy grubs Mere found in 

 fi'ozen earth in the field. In the boxes, however, they did not with- 

 stand cold very much below freezing. Experiments were made to 

 ascertain the iwssibility, or feasibility, of starvation, with the result 

 that very few larv.e were affected even when kept for mouths in soil 

 more free from organic matter than that of any cultivated field would 

 be, and it does not seem at all probable that this method, which has 

 been recommended by some of <mr best entomologists, is of any value. 

 A dry soil is very unfavorable to the larva', and if very dry they 

 speedily perish. On the other hand, they are not unfavorably affected 

 by a moist or even very wet soil, at least for some time. 



Several of the potash salts were used in the form of strong solution, 

 1 ounce in 1 ])int of water and poured over soil containing larva?. The 

 results were not such as to lecommend the use of these salts, although 

 they are far from valueless. The sulphate of potash on the whole 

 proved most useful, but to destroy any considerable portion of the 

 grubs an amount larger than wcmld generally be economical was neces- 

 sary. Common salt and wood ashes were each tested both in solution 

 and as lye and mixed with tlie soil dry, but the grubs were not seri- 

 ously injured by them. Bisulphide of carbon was more effective and 

 without doubt could be used to advantage in many cases. Kerosene 

 emulsion, however, is better in its results as well as cheaper and seems 

 on the whole decidedly preferable to any substance tried. Poured over 

 grass in dilution such that the grass was uninjured, it yet destroyed 

 most of the larvte. Red ants are a great aid in destroying tlie grubs, 

 and very likely other species than that noticed, the common red ant, are 

 equally valuable. A box in which a number of the larva? were living 

 having been discovered by the ants they at once took possession and 

 promptly destroyed every one of them, and this leads to the conclusion 



