17 
larvae has the effect of impairing the vitality of the plant and causing 
the leaves to wilt and die. Upon attaining full grpwth the larva 
makes a cell of castings and woody fibers in which to transform to 
pupa and ultimately to adult. The pupal stage varies from eight to 
eleven days, according to temperature. In the District of Columbia 
the pupal period was passed in nine days in warm August weather; 
larva? have been noted to obtain full growth by the second week of 
July, and imagos of the new generation have appeared as early as 
July 24. In more northern localities development is slower, the 
beetles seldom appearing before August and maturing as late as Sep- 
tember. The pupal cells may be constructed in any portion of the 
stem, but are preferably placed near the roots, where the stalk is 
firmest and where the beetles will be best protected during their hiber- 
nation. All beetles mature by September and hibernation is there- 
fore always as a beetle, and the knowledge of this fact is of value in 
the control of the species, as will presently be fully explained. 
NATURAL ENEMIES. 
The potato stalk weevil is subject to the attack of a small dark- col- 
ored four-winged parasite ffy known as Siglaphus curcalionis Fitch, a 
well-known Irymenopterous enemy of the plum curculio. A species of 
chalcis fly was reared at this office from material received in 1896 from 
Yorkana, Pa. The larvae, according to Professor Gillette (Insect Life, 
Vol. Ill, p. 247), sometimes fall a pre}^ to wireworms. Messrs. Kirk- 
patrick & Son, previously mentioned in connection with recent injury, 
sent the larva of Dratferius amabilis July 2, 1897, with the statement 
that several of these wireworms were noticed in the stems of potato 
that had been infested by the weevil. 
REMEDIES. 
The potato stalk weevil is not a difficult insect to deal with. About 
the only remed}^ that is necessary is to pull up infested vines as soon 
as they commence to wilt and show evidence of attack, and spread 
them out so that they will be exposed to the sun and will dry and thus 
prevent the escape of the insects which they contain. Then all stalks 
in infested fields should be burned as soon as the crop is off. By thus 
destroying the weevils the crop of insects for another year will be 
greatly lessened. In connection with this remedy it is also advisable 
to keep down all Solanaceous weeds which serve as breeding places for 
this and other insects and are therefore a standing menace to the culture 
of potatoes. The time for the destruction of the weeds is in July, 
after they have attracted the hibernated beetles to them for egg laying, 
or any time thereafter before the seeds are ripe. For perfect success 
in this treatment of potato fields, the cooperation of neighboring farmers 
is essential. 
23987— No. 33—02 2 
