SCOLYTID.E. 



491 



The genus Pliytobius is closely allied to the preceding; the 

 European P. velatus Beck has the habit, as we learn from 

 Gerstaecker (Handbuc'h der Zoologie) of living under water. 



The Potato-stalk Weevil, Baridius trinotatus Say (Fig. 470 ; 

 larva and pupa ; 471, adult), is a common species in the Mid- 

 dle and Western States, where it causes the stalk to wilt and 

 rlie, hence all stalks so affected should be burnt. " The beetle 

 is of a bluish or ash gray color, distinguished as its name im- 

 plies, by having three shiny black impressed spots at the lower 

 edge of the thorax. The female deposits a single egg in an 

 oblong slit about one-eighth of an inch long, which she has pre- 

 viously formed with her beak in the stalk of the potato. The 

 larva subsequently hatches out and bores into the heart of the 

 stalk, always proceeding downward towards the root. When 

 fully grown it is a little over one-fourth of an inch long, and is 

 a soft, whitish, legless grub, with a scaly head." (Riley.) The 

 larva of B. vestitus Sch. (Fig. 

 472), infests the stems of 

 the tobacco plant in Mexico. 



Mr. Himtington has ob- 

 served the Grape Cane gall 

 curculio, Baridius Sesostris 

 Lee. (Fig. 473) in the larval 

 state in large bunches near the joints of the Clinton grape on 

 Kelly's Island, near Sandusky, Ohio, and has also found the 

 beetle in considerable numbers. The larva closely resembles 

 that of the Potato Baridius. Riley states that the gall 

 is formed during the previous autumn while the tender 

 cane is growing. "It has almost invariably a longitu- 

 dinal slit or depression on one side, dividing that side 

 into two cheeks, which generally have a rosy tint." 

 It pupates late in June, and early in July the adult Fig. 472. 

 appears. It may be known by its polished elytra and punc- 

 tured thorax. It is pale reddish, with a stout beak, equalling 

 the body in length, and each elytron has a swelling on the 

 outer edge near the base, and another near the tip. It is a 

 tenth of an inch long. It is the Madams vitis of Riley. 



SCOLYTID^E Westwood. These cylindrical bark borers are 



