527 



oviposition of the beetles, and this seems to deter them from depositing 

 their oggs or, if they are deposited, breaks up the egg-chambers which 

 are only a few inches below the surface, and prevents the hatching 

 of the young grubs. By cutting these fields late, in November or 

 December, it is possible to ratoon them again, wliile httle injury is 

 apparent from grubs. Any grubs that survive the December culti- 

 vation would be destroyed by a subsequent ploughing preparatory 

 to early planting. The importance of ploughing up all cane stubble 

 is particularly emphasised, as it constitutes a breeding ground for all 

 sorts of cane pests. Mauritius beans were tried as a cover crop, but 

 did not afford complete protection. 



Lepidiofa frenchi has been observed to oviposit in almost any 

 uncultivated areas where blady- grass is growing, and it is unsafe to 

 use grass-land immediately for sugar-cane if the small grubs are very 

 abundant during ploughing. L. rothei has previously been reported 

 as occurring in considerable numbers in December and January [see 

 this Review, Ser. A, vi, p. 294]. Females lay from 4 to 12 eggs about 

 7 t^ 12 days after mating ; these hatch after a period of 9 to 11 days, 

 the first larval stage occupying about 10 weeks, and the second stage 

 about 6 weeks. Third stage larvae were obtained in breeding cages 

 by 28th April. Among L. albokirta, observed on volcanic land at 

 Meringa, 10 per cent, of the grubs, having eaten every root of cane, 

 were devouring the last few inches of stalk still attached to the old 

 setS; indicating that these grubs continue to feed upon such vegetable 

 tissue as may be readily available rather than travel in search of more 

 palatable food. The remaining 90 per cent, of larvae unearthed on 

 this occasion had formed cells in the hard soil preparatorv^ to pupating, 

 70 per cent, of these being found at depths varying from 11 to 18 

 inches. 



Davis (J. J.). The Relation of Agronomy to Entomology : a Practical 

 Illustration. — Canadian Entomologist, London, Ont., 1, no. 8, 

 August 1918, pp. 253-255. [Received 12th October 1918.] 



These notes are Avritten with a view to emphasising the importance 

 of more intimate correlation between agronomy and entomology. 

 Illustrations of remedial measures directed against insect pests, but 

 which are also of benefit to agriculture, are observed in the case of 

 rotation of crops for Diabrotica longicornis (northern corn root worm) 

 and for Aphis maidiradicis (corn root aphis). The time of sowing 

 wheat to avoid the Hessian fly [Mayetiola destrvctor] coincides with 

 the proper date for so^^^ng, apart from insect prevalence, while 

 ploughing under the stubble to destroy the summer brood of the fiv 

 is also a good agricultural practice. With regard to the control of 

 Lachnosterna, spp. (white grubs), many facts are adduced in evidence 

 that May beetles will not deposit their eggs in numbers in ground 

 that is covered with well-grown clover. The natural conclusion is. 

 to substitute clover for timothy grass in the rotation and to follow 

 clover with maize, especially in the year following an abundance of 

 May beetles. A rotation that is considered advisable in land infested 

 by white grubs in northern Illinois and southern Wisconsin, and that 

 is approved by agronomists, is oats or barley followed by clover and 



