BIOLOGY OF THE SMARTWEED BORER, PYRAUSTA 

 AINSLIEI HEINRICH 1 



By George G. Ainslie, Entomological Assistant, and W. B. Cartwright, Scientific 

 Assistant, Cereal and Forage Insect Investigations, Bureau of Entomology, United 

 States Department of Agriculture 



INTRODUCTION 



The attention of the senior author was first called to the smartweed 

 borer in 191 2, when hibernating larvae were found in cornstalks at Frank- 

 lin, Tenn. The economic status of this insect was undetermined at that 

 time, but field and rearing records made in Tennessee and neighboring 

 States since then have indicated that it is of no importance as a pest. At 

 present, however, it is of considerable interest because of its similarity, 

 both in habits and appearance, to the European corn borer (Pyrausta 

 nubilalis Hiibner). Until recently, also, it has been confused with 

 another similar species, P. penitalis Grote, which feeds on lotus; and 

 the purpose, in part, of this paper is to rectify this error. 



Although Dr. E. Mosher (7, p. 264) 2 recorded differences of structure 

 and the present authors found distinct variations in habit between the 

 insect under discussion and the true Pyrausta penitalis, the former was 

 first definitely recognized as an undescribed species by Mr. Carl Heinrich 

 (<5) of the Bureau of Entomology. Mr. Heinrich gives in detail the 

 morphological characters separating the species nubilalis, penitalis, and 

 ainsliei in all stages. Chittenden (1) has well summarized all the avail- 

 able records of the smartweed and lotus borers, although he was not 

 aware that two species were included. 



DISTRIBUTION AND HOST PLANTS 



The smartweed borer is known to occur in Massachusetts, New York, 

 Pennsylvania, Ohio, and Illinois ; and the writers have taken it at numer- 

 ous points in Tennessee and Kentucky and at Clemson College, S. C. 

 Polygonum pennsylvanicum, its principal food plant, occurs throughout 

 the eastern half of the United States, and it is likely that the distribution 

 of the borer is coextensive therewith. 



The plants in which the larvae are found must be divided into two 

 groups, namely, food plants proper and shelter plants. 



1 In recent papers by Flint and Malloch (j, 4), the name Pyrausta obumbralalis Lederer (misspelled 

 obumbratilis) is used for this species. While it is possible that ainsliei will prove to be a synonym of obum- 

 bratalis, it seems inadvisable at this time to use this latter name for this species, for, until Lederer's type 

 can be examined and its exact identity and relation to the other species under discussion determined, its 

 use will simply add confusion to a matter which seems in a fair way to be solved. 



2 Reference is made by number (italic) to "Literature cited," p. 844. 



Journal of Agricultural Research, Vol. XX, No. n 



Washington, D. C Mar. 1, 1921 



wz (837) Ke >' No - ^"93 



