106 [Assembly, 



The Potato Stalk "Weevil. 



Trichobaris trinotata (Say). 



A communication to the American Rural Home, of July 24, 1886, 

 gives information of a severe attack of the above named insect 

 upon the potato crop in Arizona, from which it will be seen that 

 it is a more serious evil in that region than it has thus far been in 

 the Eastern States. This may, in part, be due to the larger form 

 that the beetle assumes in its western distribution — in Upper and 

 Lower California and in Arizona, according to Dr. Le Conte 

 (Rhynchophora of Worth America, 1876, p. 288) : 



To the Editor : 



Sir. — I send inclosed, specimens of a bug that has almost entirely 

 destroyed the potato crop in this section this season. I never saw 

 it before, nor have any of my neighbors. It bores into the heart of 

 the stalk at the top of the ground while small, in the larva stage, 

 and, completing its growth, passes the chrysalis stage and emerges 

 the specimens inclosed, leaving the plants in a shriveled and dying 

 condition. There are from one to six or eight worms in almost 

 every vine, sometimes boring the entire inside out of the stalk for 

 from three to ten inches of its length. 



Can you tell me what it is ? Is there any remedy or preven- 

 tive ? By answering the above you will greatly oblige the readers 

 of your paper in this place. We plant our potatoes in this climate 

 in February, and they ripen in June. Some of the earliest escaped, 

 as the potatoes were sufficiently matured not to be much affected, 

 but the later ones are almost a total failure, as the tubers remain in 

 whatever stage of growth they are when the worms begin on the 

 vines. 



GEO. P. DYKES. 



Zenos, Maricopa County, Arizona. 



The above communication gives us some additional knowledge 

 of the destructive habits of the larva of a snout beetle (one of the 

 Curculionidce), popularly known as the potato stalk weevil, and 

 scientifically as Trichobaris trinotata (Say). It is about three- 

 twentieths of an inch long; oval, with the characteristic projecting 

 curved beak of the curculios, of an ash-gray color from its cloth- 

 ing of short gray hairs, and with three small black spots (whence 

 its specific name), one on each hind angle of the thorax and another 

 behind its middle angle. It is figured in Dr. Harris' Treatise on 

 Insects Injurious to Vegetation, as Baridius trinotatus, and referred 

 to as not known in New England, but occurring in the Middle 



