838 Journal of Agricultural Research voi.xx, No. « 



FOOD PLANTS 



Riley (according to Chittenden, 1, p. 454), who first noted what was 

 probably this species, found larvae in stems of Polygonum incarnatum; and 

 Hart (5, p. 182) mentions that it has been reared from the same species 

 at Urbana, 111. Chittenden states that there is a moth in the National 

 Museum reared from stems of Polygonum hydropiperoides . The foregoing 

 references occur under the name of Pyrausta penitalis, but relate without 

 doubt to Pyrausta ainsliei. After investigating the matter in New York, 

 Dr. E. P. Felt writes that in his opinion — 



Pyrausta ainsliei occurs very commonly in Polygonum pennsylvanicum in this section 

 [New York] and much more rarely in P. lapathifolium. 



Mr. D. J. Caffrey writes that Pyrausta ainsliei has been reared from 

 Polygonum persicaria in Massachusetts. 



The work of the present authors indicates very clearly that south of the 

 Ohio River, at least, Pyrausta ainsliei breeds only in Polygonum pennsyl- 

 vanicum. Despite the most careful and persistent search they have failed 

 to find either larvae or eggs, or any trace of them, on plants of any other 

 species even though growing in the immediate vicinity of Polygonum 

 pennsylvanicum and often in the same clump. The species of the genus 

 Polygonum are often confused, and determinations of plants for 

 entomological purposes are so often made carelessly or from insufficient 

 material that further work appears necessary in order that the occurrence 

 of this borer in species other than Polygonum pennsylvanicum may be 

 verified. As Polygonum incarnatum is now considered a synonym of 

 Polygonum lapathifolium the following are here listed as reported natural 

 food plants of Pyrausta ainsliei: Polygonum pennsylvanicum, Polygonum 

 lapathifolium, Polygonum hydropiperoides , and Polygonum persicaria. 



It should be stated that although never found on them in the field, 

 larvae have been reared from eggs to full-size caterpillars on leaves of 

 curled dock (Rumex crispus) and buckwheat (Fagopyrum fagopyrum), 

 both of which are close relatives of Polygonum. Leaves of all com- 

 mon weeds and plants were offered to the larvae, but in every case except 

 the two mentioned above they were either refused or only slightly 

 gnawed. On leaves of lotus (Nelumbo lutea) the larvae in several experi- 

 ments starved to death after merely pitting the leaf surface. Mr. 

 Heinrich's statement (6, p. 175) that we have reared these larvae to 

 maturity on N. lutea is an error. 



SHELTER PLANTS 



The other group, shelter plants, includes all plants the stems of which 

 are entered by larvae seeking winter quarters. The list of such plants 

 will eventually contain practically all the pithy stemmed weeds and plants 

 the bark of which is not too dense to permit the entrance of the larvae. 

 Some of the larvae remain in the stems of smart weed, but for some 



