Mar. i, 1921 Biology of the Smartweed Borer 839 



obscure reason many leave their food plant and seek entrance to anything 

 that will give them dry quarters through the winter. The plants in 

 which larvae have been found by the authors are as follows: Corn (Zea 

 mays), ragweeds (Ambrosia triftda and Ambrosia artemisiaefolia) , cockle- 

 bur (Xanthium communis), goldenrod (Solidago spp.), aster (Aster spp.), 

 timothy (Phleum pratense), cattail (Typha latifolia), beggartick (Bidens 

 bipinnata and B. jrondosa), and numerous other wild plant stems not in 

 condition for determination. Dr. Felt adds Brassica arvensis and Chit- 

 tenden (1) lists raspberry stems, to which the larvae gained entrance 

 through the cut ends. Eupatorium sp., in which larvae were found in 

 Missouri according to Chittenden, is also undoubtedly a shelter plant. 

 Aside from Polygonum spp. the foregoing plants are in no sense food 

 plants. The larvae burrow the stems enough to construct a cavity 

 sufficiently large to contain them ; and even in this process, as the authors 

 have observed, they do not swallow the plant tissue but eject it from the 

 mouth. It is this habit of seeking shelter wherever it may be found, es- 

 pecially in cornstalks, that seems likely to lead to some confusion, for 

 the larvae are so similar to those of Pyrausta nubilalis, the European corn 

 borer, that without careful laboratory study the two can not be differ- 

 entiated. 



SEASONAL HISTORY AND HABITS 



In Tennessee there are two generations of the smartweed borer each 

 year. Adults reared at Knoxville emerged from May 26 to October 30 

 with two well-defined periods of maximum abundance, the first from 

 June 20 to July 5 and the second from August 1 8 to 30. Moths emerging 

 in June at once oviposit, and the resulting larvae complete their growth 

 early in August and immediately pupate in their larval burnyws in the 

 smartweed stems. The moths emerge later in the same month and give 

 rise to the second generation of larvae, which reach full growth before 

 winter and without further feeding remain in the food or shelter plants 

 unchanged until they pupate in May and June of the following year. 



Very few published data are available. Hart (5, p. 182) states that 

 moths (probably of this species, as there is no Nelumbo near Urbana) were 

 taken at light at Urbana, 111., from May 19 to August 6, and that a single 

 moth was reared July 1 . In Missouri moths issued from smartweed from 

 May 29 to June 6, and others are labeled October 9. Although scat- 

 tering data on this species are included in his paper, Chittenden's conclu- 

 sions do not agree with the actual life history as the authors have found it, 

 and his statements must be taken, in the main, to apply to Pyrausta 

 penitalis. 



In a reared series of larvae from eggs hatching August 16 a number of 

 moths emerged October 13 and 15. This is difficult to explain except on 

 the ground of abnormal conditions, for it does not seem possible that in 

 nature moths emerging so late could produce another generation, and 



