241) BOARD OF AGRICULTUEE. 



the English cockchafer, or dor beetle (Melolontlia vulgaris). 

 But the English chafer becomes an imago in January or Feb- 

 ruar}^ and comes forth into active life in May, just four years 

 from the deposit of the egg. Supposing our Cotaljm to take 

 on the imago form in autumn, and to spend its life from that 

 time to the next May iu the ground, it would be live years 

 old when it makes its debut as an arboreal insect." It is 

 possible that Dr. Lockwood may be in error regarding the 

 age of tills beetle, as M. T. Keiset says in France this insect 

 is three years in arriving at its perfect beetle state. The fol- 

 lowing remarks on the habits of the European chafer may aid 

 observers in this country in studying the habits of our native 

 species. M. Reiset says (see "Cosmos" as translated in the 

 "American Naturalist," vol. II. , p. 209) " that this beetle in the 

 spring of 18G5 defoliated the oaks and other trees, while im- 

 mense numbers of their larvie in the succeeding 3'^ear, 1866, 

 devoured to a fearful extent the roots of garden vegetables, 

 &c., at a loss to the department of the lower Seine of over 

 live millions of dollars. This insect is three years in arriving 

 at its perfect beetle state. The larvie hatched from eggs laid 

 by the beetles which appeared in such numbers in 1865, passed 

 a second winter, that of 1867, at a mean depth in the soil of 

 forty one -hundredths of a metre, or nearly a foot and a half. 

 The thermometer placed in the ground (which was covered 

 with snow,) at this mean depth, never rose to the zero point* 

 as minimum. Thus the larvie survivf^rl after being perfectly 

 frozen (probably most subterranea li arvie are thus frozen, 

 and thaw out in the spring at the approach of warm weather) . 

 In June, 1867, the grubs having become full-fed, made their 

 way upwards to a mean distance of about thirteen inches 

 below the surface, where, in less than two months, they all 

 changed to the pupa state, and in October and November the 

 perfect beetle appeared. The beetles, however, hybernate, 

 remaining below the surface for a period of five or six months 

 and appearing in April and ISIay. The immature larvie, 

 warned Jn'the approaching cold, began to migrate deep down 

 in the soil in October, when the temperature of the earth was 

 ten degrees above zero. As soon as the snow melted they 

 gradually rose towards the surface." 



* By the centigrade thermometer. 



