WEEVILS WHICH AFFECT IRISH POTATO, SWEET 

 POTATO, AND YAM 



By W. DwiGHT Pierce, 



Entomologist, Southern Field Crop Insect Investigations, Bureau of Entomology, United 

 States Department of Agriculture 



INTRODUCTION 



In a previous article ^ the writer discussed three important Andean 

 weevil pests of the potato tuber {Solanum tuberosum). In the present 

 paper a fourth potato tuber weevil is described and notes are presented 

 on three weevils which attack the tubers of sweet potato (Jpomoea 

 batatas) and one which attacks the tubers of the yam {Dioscorea batatas). 



WEEVILS WHICH AFFECT IRISH POTATO TUBERS 



The native home of the Irish potato is the west coast of South America, 

 and here we find that the crop has a series of characteristic pests which 

 may be easily disseminated in shipments of potatoes. As stated above, 

 the writer has described three of these species in a previous paper. The 

 description of the larva of one of them is now added and a new species 

 described. In order that these weevils may be easily distinguished one 

 from another by the man in the field the following table has been con- 

 structed : 



TABLE OF IRISH POTATO TUBER WEEVILS 



1. Prostemum grooved for reception of beak; mandibles without deciduous piece; 



pronotum with, a deep median furrow widened angularly at middle and also 



behind Rhigopsidius tucumanus Heller. 



Prostemum not grooved for reception of beak; mandibles with deciduous piece . . 2 



2. Mandibles with tooth beneath; scrobes abruptly and broadly terminated, not 



extending beneath ? 



Mandibles without tooth beneath; scrobes narrowing and extending beneath; pro- 

 thorax not as wide as elytra, angulate and broadest in front of base 



Premnotrypes solani Pierce. 



3. Prothorax broader than elytra, subquadrate, with sides parallel to apical third, 



thence strongly narrowed ; sides of elytra smooth . . Trypopremnon laiithorax Pierce. 

 Prothorax acutely angulate at sides, widest before base; sides of elyixa tuberculate, 



Trypopremnon sanfordi, n. sp. 



' Pierce, W. D. new potato weevus from andean south America. In Jour. Agr. Research, v. i, 

 no. 4, p. 347-352, 3 fig., pi. 39-41- 1914. 



Journal of Agricultural Research, Vol. XII, No. 9 



Washington, D. C. (601) Mar. 4, 191S 



ms Key No. K— 61 



