334 ECONOMIC ENTOMOLOGY 



generation about 43 days and there are probably not more than 

 four or five generations in a season. 



Life-history. — "The egg is deposited by the female weevil in a 

 cavity formed by eating into a cotton square or boll. The egg hatches 

 in a few days and the footless grub begins to feed, making a larger 

 place for itself as it grows. During the course of its growth the larva 



sheds its skin at least three times, the 

 third moult being at the formation 

 of the pupa, which after a few days 

 sheds its skin, whereupon the trans- 

 formation becomes completed. These 

 immature stages require on the aver- 

 age between 2 and 3 weeks. A fur- 

 F I G . 216 . — Cotton boll-weevil: thcr period of feeding equal to about 

 S^SetatVaTSL.''',?/";;/^':"; ™e-third of the preceding develop. 



mental period is required to perfect 

 sexual maturity so that reproduction may begin" (Hunter and 

 Pierce). 



Strawberry Crown Borer {Tyloderma fragari(B Riley). Adult. — 

 A small dark snout-beetle, )^ inch long; head and thorax black; each 

 wing-cover with 3 black spots. Hibernates. 

 Eggs. — Probably laid in the crown. 



Larva. — Small white grub mining out interior of the crown; )^ 

 inch long; legless; head yellowish-brown. Matures in August. 



Pupa. — Formed in the larval cavity. Adults emerge in late 

 summer and fall. 



Potato Stalk Borer (Trichobaris trinotata Say). — Burrows in the 

 stalks of potatoes. 



Adult. — A snout-beetle, 3^^ inch long, dull black to light grey; three 

 black spots at union of prothorax and wing-covers; snout curved and as 

 long as prothorax. Front of prothorax orange-yellow. Hibernates 

 in burrows in the old stalk. 



Eggs. — Small, oval, pearly white; laid singly in punctures in 

 stalks. 



Larva. — Yellowish-white; head light brown; legless; ^^ inch long. 

 Burrows in the stalks. 



Pupa. — At first yellowish-white, later dull brown; 3^^ inch long, en- 

 closed in oval greenish cocoon of fras; duration about a month. 



