INSECTS INJURIOUS TO POTATOES AND TOMATOES 257 



in spring and into June. These beetles are about one-fourth of an 

 inch long, with a long, black beak or snout, and are marked at the 

 base of the wing-covers by three black spots which give the insect 

 its specific name, trinotata. Each beetle punctures a small hole in 

 the base of a stem by means of its beak, hollows out a small cavity, 

 and there lays a single small, oval, whitish egg. From these eggs 

 some small, white grubs with brown heads hatch in a few days and 

 commence to bore into the stalk. These grubs keep eating, either 

 in the main stalk or branches, from August 1st to September 1st, 

 when they have become full grown. At this time the grubs are 

 about one-half an inch long, of a dirty white or yellowish color, 



FIG. 221. Potato stalk-borer (Trichobaris trinotata}. Larva, pupa and adult. 

 (After J. B. Smith.) 



with a yellowish-brown, horny head, and without legs. About the 

 middle of August, as a general rule, the grubs construct small, oval 

 cocoons of chips and fibres in the stalk of the vine near the sur- 

 face of the soil, and there transform to the pupae. During late 

 August and September the mature beetles shed the pupal skins, in 

 which they have remained dormant for the last few weeks, but 

 remain in the vines during the winter, and do not come forth till 

 the following spring. 



Remedies. On account of its internal feeding habits no poison 

 can be successfully used against this pest, and the only remedy, 

 but a good one, is to rake up the vines and burn them as soon as 

 the potatoes have been dug. As this insect also feeds upon the 

 Jamestown weed, horse-nettle, and other weeds of the Nightshade 

 family, or Solanacece, these should be cut down very closely. 



