60 EXPERIMENT STATION RECORD. 



The author states that the pest is rapidly spreading and will soon be found 

 oyer all the citrus section of Florida. While it usually does little damage, 

 it is capable of causing an almost total loss of the year's crop and is a severe 

 check to growth. " Unless preventive measures are taken, a severe attack will 

 be followed by a marked rise in the amount of purple scale, which will inflict 

 equal or greater damage. The miscible oils are effective against the early 

 stages of the larvae of the woolly white fly. Both the red and brown fungi 

 have been found growing sparingly on the woolly white fly. A species of 

 Cladosporium probably sometimes kills up to 80 per cent. The woolly white 

 fly is heavily parasitized by a minute hymenopteron, which sooner or later 

 controls an outbreak. Because of this it probably will never develop into as 

 permanently serious a pest as is the common citrus white fly. The parasite 

 apparently does not control the late winter brood." 



Recent Illinois work on the corn-root aphis and the control of its injuries, 

 S. A. Forbes {IlUnois Sta. Bui. 178 {1915), pp. 405-466, figs. iS).— This bulletin 

 reports the results of work with the corn-root aphis carried on from 1907 to 

 1910 in continuation of that of 190.5 and 1906 (E. S. R., 21, p. 57). A circular 

 relating to this work has been noted (E. S. R., 28, p. 855). 



" The principal measures of protection against the corn-root aphis are rota- 

 tion of crops; an early and deep plowing, followed by the repeated deep 

 disking, of com ground heavily infested by ants or known to have borne a crop 

 injured by the root aphis; and the use of repellent substances at planting 

 time, not by direct application to the seed (which is dangerous to germination 

 and early growth) but by previous mixture with chemical fertilizers or other 

 powdered substances, to be dropped with the seed by means of a fertilizer 

 dropper attached to the corn planter. . . . 



" Experiments of 1907 show that wet weather at planting time may either 

 result in serious injury to the seed if repellents have been applied to it direct, 

 or in such washing away of the repellent substances that they produce no 

 effect, either on the seed or on the ants and aphids, the character of the 

 effect apparently depending on the amount of rainfall and on its relation to the 

 time of actual planting. Comparative experiments show that the injurious 

 effects reported were not due, as at first surmised, to differences in the 

 quality of the repellents used in different operations. Laboratory experiments 

 with a considerable variety of repellents applied by uniform methods to colonies 

 of the cornfleld ant in a special cage showed that oil of tansy, oil of lemon, 

 anise oil, tincture of asafetida, apterite, and vermicide were very strongly 

 repellent; that kerosene, camphor, and coal tar were less effective repellents; 

 and that a considerable number of other substances tested were, if repellent 

 at all, too slightly so to make them practically useful. 



" Additional field experiments made in 1908, in a spring season which proved 

 to be very wet, resulted in no injui-y to the seed, and on the other hand in 

 no benefit to the crop, flooding rains apparently washing away the repellents 

 before they could take effect upon either the seed corn or the insects. 



" Experiments made in 1910 with tincture of asafetida and oil of lemon, ap- 

 plied first to bone meal which was then dropped with the corn by means of a fer- 

 tilizer dropper attachment to the planter and tested by the yield at corn husking, 

 showed a gain of 5.G bu. per acre by the use of asafetida and 10.8 bu. per acre 

 by the use of oil of tansy, the first gain being obtained at a cost for materials 

 and additional labor of 34 cts. a bushel, and the second gain at 27 cts. a bushel. 

 This result was the more encouraging since a very unfavorable spring caused 

 an unusually poor stand and retluced greatly the general yield of com. In a 

 good corn season the gain would have been greater for the same cost. 



