ELISHA MITCHELL SCIENTIFIC SOCIETY. 69 



NATURAL HISTORY. 



Number of Annual Generations.— There are at least two genera- 

 tions each year in this latitude, though the periods of transforma- 

 tion do not seem to be very well marked, as variations in the length 

 of the larval stage cause an overlapping of the broods. The ex- 

 tremes of variation may extend so as to make it possible that some 

 transformations are taking place at all times of the year, where the 

 temperature of the manufactory is such as to permit the activity of 

 the insect in some of the rooms. 1 have seen the beetles in the act 

 of copulation in January, and during the periods when the majority 

 of the transformations are taking place the larvae may be found in 

 very different stages of development. 



One of these periods occurs during the month of June. June 28 

 I placed beetles in the act of copulation in small phials and added a 

 minute quantity of prepared cigarette tobacco. In from two to 

 three days the egers were deposited. 



Egg.— The egg is opaque, white, elongate, oval, or elliptical, ,4°^™ 

 long by .22""" in diameter in the broadest part. Micropyles .04°»™ 

 long covering one end. The number of eggs deposited by the beetles 

 observed varied from 40 to 75. In the phials in which was placed 

 a few threads of prepared cigarette tobacco the eggs were scattered, 

 some upon the glass and a few on the tobacco. In the phials con- 

 taining bits of leaf tobacco the eggs were laid in irregular patches 

 between the portion of a fold. In about 11 days the egg hatches. 



Length of Larval Stage.— The \iirvail stage at this season averages 

 from 60 to 70 days. Eggs which were deposited June 30 hatched 

 July 11, and some larvae constructed cocoons September 11. From 

 5 to 7 days afterward they transform to pupae. The larva is whitish 

 and covered with very slender white hairs. It measures from 4™™ 

 to 4^^"°^ in length. 



Cocoon. — The cocoon is of a papery texture, formed of finely di- 

 vided particles of material which is near at hand, cemented together 

 with viscid liquid. In the case of cigarettes the larva usually leaves 

 the cigarette and makes the cocoon against the paper package, or 

 in some of its foldings, or in a corner of the box. In this case the 

 cocoon is made chiefly of paper. In leaf tobacco the larva usually 

 remains among the foldings of the leaves and constructs the cocoon 

 from tobacco. It does not use the hairs from the body in the con- 

 struction of the cocoon. 



The beetle is of a brown color, and about 2f°^ long. It has a 



