284 



two vertical glass plates less than half an inch apart. The cages were 

 shielded from the hght except at the moment of examination By 

 regulating the distance between the plates, larvae of any size could be 

 viewed from at least one side. The results were as follows : — (1) No 

 daily migration was observed ; movements and feeding occurred only 

 in warm weather, activity reaching a maximum during the heat of the 

 day ; the optimum temperature was between 60° F. and 65° F. 



(2) The food apparently consisted entirely of the roots of plants. 



(3) Larvae were reared from 5th May to 18th July in soil without 

 apparent food ; the soil was then allowed to dry and on 22nd October 

 two larvae were ahve and active ; starvation methods for control are 

 therefore useless. (4) Poisoned bran mash was not eaten by the larvae 

 and was thus of no value. (5) Sodium arsenite, into which grass roots 

 were dipped before planting, resulted in the death of 22-2 per cent, of 

 Jarvae in four days ; no injury to the grass was observed. Corrosive 

 subhmate used on one plant caused a mortaUty of 50 per cent., but the 

 plant died, since the roots were entirely eaten. (6) Kerosene emulsion 

 and Black Leaf 40, at the ordinary strengths, were useless. (7) 

 Creosote acted as a repellent and did not injure the treated plants. 

 In the control pots a mortality of 15-9 per cent., due to bacterial and 

 .other diseases, was observed. Results in connection with temperature 

 and nature of food supply seemed most significant. 



Davis (J. J.). A Progress Report on White Grub Investigations.— 



Jl. Econ. Entom., Concord, ix, no. 2, April 1916, pp. 261-281, 

 3 plates, 1 table. 



Lachnosterna investigations carried out at Lafayette, Indiana, have 

 included a study of the hfe-history, habits and embryology of various 

 species, and a determination of the distribution of species throughout 

 the country in relation to soil, timber, farming methods, etc. L. tristis 

 invariably has a two-year cycle in the latitude of Lafayette, while 

 L. arcuata, L. fusca, L. vehemens, L. rugosa, L. ilicis, L. grandis, 

 L. fraterna, L. hirticula, L. inversa, L. bipartita, and L. congrua have a 

 three-year cycle. L. crenulata and L. crassissima usually require three 

 years for development, but this may be extended to four years, while 

 the normal three-year cycle of L. gibhosa, L. burmeisteri and L. implicita 

 may be reduced to two years. The length of the hf e-cycle is influenced 

 by latitude, increasing in the more northern States and decreasing in 

 the more southern. In the latitude under consideration, the hfe- 

 history of the economic species of Lachnosterna is as follows : — The 

 eggs are laid singly in balls of earth in soil covered with grass or small 

 grain ; more than 50 eggs are deposited by each female. The larvae 

 feed on young roots and decapng vegetation until autumn., when they 

 go deeper down and hibernate in a special cell. Activity is resumed in 

 May and continues until the beginning of October, when hibernation 

 occurs. In the spring of the third year, feeding continues until Ijie 

 beginning of June, when the pupal cell is formed. The prepupal stage 

 lasts about two weeks and the pupal from three to four weeks. Adults 

 emerge from the soil at the end of April or beginning of May in the 

 fourth year. The most severe injury occurs during the second year, 

 but in northern Wisconsin, where the Hfe-cycle is extended by one year, 

 damage occurs during the two seasons following the year of oviposition. 



