LIFE HISTORY OF BOTH SPECIES. 



The life history of our two chestnut weevils is so similar as to be 

 practically the same for both species. There are, however, minor 

 differences. These, as well as related nut and acorn weevils, hibernate 

 exclusively in the larval condition and in the soil. Roth make their 

 first appearance at about the same time — with the first bloomino- of 

 chestnuts — but this period may vary from late in June to July, 

 according to locality and season, or, more properly speaking, the 

 mean temperature. At this time the beetles are found rarely and 

 scatteringly, and as oviposition has not been observed then it is 

 doubtful whether it begins until considerably later. What function 

 these early arrivals fulfill is jDroblematical. The beetles increase in 

 number as the nuts approach maturity, or until about the middle of 

 September or a little time before the nuts are first marketed. Then 

 they may be seen in greater abundance, several pairs, frequently of both 

 species, often occurring on a single bunch 

 of burrs (fig. 8). As it requires about two 

 weeks for the egg to develop, it is not prob- 

 able that they are laid much earlier than 

 when the nut begins to form. From exam- 

 ination of many burrs gathered in the fall 

 of 1904 by Mr. F. C. Pratt, of the Bureau 

 of Entomology, who visited some of the 

 principal chestnut groves of Pennsylvania ^^^'- e-Lesser chestnut weevil 



, -IT-- • • , ii . <• {BalaniniiK rectus): Pupa. iTom 



and \ irginia at the urgent request of grow- side, at left; ventral view at 

 ers in those States, it is deduced that the "s^^- Enlarged (author'.s 



n -I •-! 1-1/1-I -1 illustration). 



first eggs deposited are laid (seldom and 



very sparingly) in the soft, woolly material surrounding the forming 

 nut; but later they are inserted in the kernel just under the inner 

 skin, and occasionally they are deposited somewhat more deeply. In 

 no case has the egg been found in the outer husk. 



Eggs are laid singly, but many are ])laced in a single nut, as high as 

 40 or more (of the smaller weevil) in imported nuts, and as many as 

 9 in native nuts. The larvae when hatched feed on the tissue of the 

 growing kernels, enlarging with their own growth the cells thus made. 

 When, as is usual, several larvee inhabit the same nut, the interior is 

 more or less completely hollowed out, and large masses of excrement 

 are left behind (fig. 9). 



By the end of Sejjtember or the first week of October the beetles dis- 

 appear. At about the same time, when the nuts first fall, the larva^ be- 

 gin to mature and issue from round orifices which they gnaw through 

 the shell and which vary in diameter from one-sixteenth of an inch, in 

 the case of the smaller species, to one-eighth of an inch in the larger 

 (see fig. 7). By the size of these holes alone it can be readily deter- 

 mined which species is the dominant one in any given locality. Rarely 



[Cir. 99] 



