THE stalk-borer: allied species and remedies. 115 



Allied Species. 

 A closely allied species is recognized in our lists, Gortyra nelris of 

 Giien6e, differing mainly in the presence of white reniform, orbicular, 

 anil cliiviform spots on the front wings, and in slightly longer and more 

 ascending palpi. Prof. Riley has reared G. nehris from the horse- weed. 

 Ambrosia trifida L., and expresses a confidence that the two forms (?) 

 iiitergrade, and are simply varieties of one species. I iiave no knowl- 

 edge of any description of the larva of G. nebrls. Prof. French states 

 that it differs from that of G. nilela, in that it pupates in the ground. 

 About twenty-five species of North America Gortynn are at present 

 known.* Of these, the larvae of the greater number, from their con- 

 cealed habits, are unknown. The larval habits of the species are not 

 uniform, for while those which Guenee includes in the genus Hydrmcia, 

 are represented by him as " not living inclosed in stems and feeding on 

 the pith, as those of Gortyna, but only concealed among the roots or 

 the basal leaves of the plants" (of which are 7iiciilans Linn,, imma- 

 nis Guen., and stramentosa Guen.), others in addition to G. nitcla 

 are known to be stalk-borers, as G. rutila Guen., in the Columbine, 

 G. ca(aj)hracta Grote, in thistle-stems, and G.flavago W.-V., of Europe, 

 in thistle-stems and burdock. It is not a little remarkable, that of 

 the old Linnsean species, G. 7iiciitans, so very common both in Europe 

 and the United States, the larva has not, so far as we have any record, 

 been identified in this country. Our ignorance of the larva of the com- 

 mon G, sera Gr.-Rob., is scarcely less remarkable.f 



Remedies. 

 When this insect occurs in the potato, its presence can be readily 

 detected by the withered stems before they have become broken down. 

 By placing the point of a penknife in the opening and slitting the 

 burrow upward, the caterpillar may be found and killed. If the field 

 be large and too badly infested to permit the employment of this 

 method, then, if the vines can be collected and burned before the month 

 of September, all the larvaB or the puptB which may be undergoing 

 their change within the stems will be destroyed. As early potatoes 

 are more liable to be infested by this borer than the later ones, the 

 burning method may be easily resorted to. The same method of treat- 



*Tlic genus, for some reason, is a very vinfortunate one in regard to its definition. It 

 appears to have been closely studied by Mr. Grote, but no two of bis several publica- 

 tions upon it agree in the species which it should embrace. In his latest publication, 

 the New Check List, several of the long recognized Gortynas, such a.s purpiiripennis, sera, 

 victiians, stramentosa, etc., are withdrawn from the genus and placed under Apamea of 

 Treitschke. 



i-For comparative remarks on several of our Gortynas, which will prove of service to 

 the student in the separation of species, the paper by Mr. Grote " On North American 

 Moths," m the Bulletin of the U. S. Geological and Geograpldcal Survey, vol. vi, 1881, at 

 pp. 268, 269, may be consulted. 



