61 



^oth against this Aphid and the ants associated with it are therefore 

 rotation of crops, early and deep ploughing and the use of repellents 

 ^t planting time. These should not be used by direct apphcation to 

 Tthe seed, but by previous mixture with chemical fertilisers. Autumn 

 ploughing and one spring disking are much more effective than spring 

 ploughing Avith no disking. Change of maize ground to oats for one 

 year, and autumn ploughing of the oat stubble, gave a 25 per cent. 

 Jarger yield than adjacent ground kept continuously under maize. 

 The root infestation of young maize on oat stubble is one-tenth that of 

 plants on old maize ground. 



PoRBES (S. A.). Observations and Experiments on the San Jos6 Scale. 



• — Twenty- eighth Report of the State Entomologist of the State of 

 Illinois, Urbana, 1913, pp. 63-79, 2 figs. [Received 2nd December 

 1916.] 



This paper deals with a series of experiments begun by the late Mr. 

 J. A. "West and completed by Messrs. W. P. Fhnt and L. M. Smith in 

 •connection with the San Jose scale [Aspidiotus perniciosus]. It has 

 been found that this scale may live and reproduce freely on ripe apples 

 picked from the tree and kept at ordinary room temperatures, and that 

 living young may continue to be produced under such conditions 

 ■during a period of eight weeks. Infested apples taken from cold 

 storage in December gave similar results, yoimg being produced on 

 these apples for 25 days. Breeding experiments conducted with the 

 object of distinguishing the descendants of the first born from those of 

 the last born of each generation, gave two successive generations of the 

 last born series in the complete year, and four such generations of the 

 first bom series. The potential rate of multiplication under optimum 

 •conditions is shown to be 32,791, 472 to 1 for the year. 



Spraying operations vnth various preparations of lime and sulphur 

 and with two brands of miscible oils justify the usual preference for the 

 sulphur solutions, especially owing to their more prolonged effect when 

 ajophed in spring. The home-made solutions were as effective as the 

 ready-made ones requiring only dilution for use. The great advantage 

 of early spraying over autumn spraying is emphasised, the effectiveness 

 of the former being some 20 per cent, greater. The possibility of 

 restoring a badly infested orchard, and maintaining it in good condition 

 ^vith one or two sprayings a year, is considered to be well established. 



Forbes (S. A.). Life-history and Habits of the Northern Corn Root- 

 worm {Diabrotica longicornis, Say). — Twenty-eighth Report of the 

 State Entomologist of the State of Illinois, Urbana, 1916, pp. 80-86, 

 1 fig. [Received 2nd December 1916.] 



In the course of some experiments with Diabrotica longicornis, no 

 •evidence of the occurrence of more than one generation in the year was 

 obtained. 



The effect of the rotation of crops on damage by this beetle is shown 

 by observations made in the amount of injury in seventy-one fields in 

 which maize had been groAvn for one, two or more years. It was found 

 that ground on which maize is grown for the first year after rotation 

 wdth other crops will not be injured at all ; maize grown for a second 

 year on the same ground is likely to become infested to an average 



