INTRODUCTION. 



105 



the end of April and beginning of May. The eggs are laid in the 

 spaces formed by .the cracking of the surface layer of the soil, 

 sometimes on the lateral roots, occasionally on the main roots, or 

 even at a distance of 1-2 cm. from them. The duration of the 

 egg stage varied, according to the temperature, from 11 to 22 

 days. According to I. M. Krasilshtshik at least 28S eggs are 

 laid by one female under natural conditions. The larvae feed 

 chiefly on the young rootlets, and pupate in the soil about the 

 beginning of June. The adults emerge during July, and may be 

 found on beet in the vicinity of flax fields, though without 

 apparently causing any appreciable damage, whereas the leaves of 

 Cirsium arvense are completely skeletonised. At the time of the 

 flax harvest the flea-beetles disappear from the fields and evidently 

 migrate. The duration of the egg, larval and pupal periods are, 

 respectively, 20, 31, and 19 days, though they vary according to 

 surrounding conditions. 



"North America. 



Epitrix parvula, E. The Tobacco Flea-beetle. 



An account of this pest is given by Z. P. Metcalf and G. W. 

 Underhill, North Carolina Agric. Expt. Sta., W. Raleigh, Bull. 

 239, April 1919 ; an abstract, from which the following is taken, 

 appeared in Rev. Appl. Ent., ser. A, vol. viii, 1920, p. 231 : — 



This flea-beetle is one of the worst pests of tobacco in North 

 Carolina. The adults hibernate near the tobacco fields under 

 leaves or grass or in other suitable places, emerging in the spring 

 as soon as any food-plant is available. There are four generations 

 a year, but the stages overlap so much that they cannot be readily 

 distinguished. The eggs, which hatch in about a week, are laid 

 from April to September near the surface of the ground under 

 the tobacco plant. The larvae feed on the roots of the plant from 

 May to October, and pupate in small cells just beneath the 

 surface of the ground. 



The greater part of the damage is done by the adult beetles, 

 which eat holes in the leaves, both in the seed-beds, where it is 

 sometimes impossible to obtain a stand of plants, and after 

 transplanting, when the plants are sometimes killed. The 

 indirect loss due to the subsequent weakening of the plant is still 

 greater, but the direct loss, which alone can be accurately 

 measured, is more than 100 lb. an acre *. 



Chcetocnema ectypa, Horn. The Desert Corn Elea-beetle. 

 An abstract, from which the following remarks are taken, is 

 given in E-ev. Appl. Ent., ser. A, vol. v, 1917, p. 434, of an account 



* Since these paragraphs were in print, there has come to hand a very full 

 account of this pest, by F. S. Ohaniberlin, J. N. Tenhet, and A. G. Boving 

 (Journ. Agric. Research, Washington, xxix, pp. 575-584, 1924). It contains 

 descriptions and figures of all the stages of the insect, and detailed bionomical 

 studies. 



