BULLETIN 265, U. S. DEPARTMENT OF AGRICULTURE. 



FOOD PLANTS. 



The dock false-worm probably confines its feeding almost entirely 

 to plants belonging to the buckwheat family (Polygonaceae) , in- 

 cluding the numerous docks and sorrels (Rumex), the knotweeds 

 and bindweeds, or wild buckwheat (Polygonum), and others. It 

 has been recorded from Polygonum bistorta in Scotland, and from 

 Polygonum sp., Persicaria sp., and Rumex sp. in Germany. In 

 America it has been recorded from the common knotweed {Poly- 

 gonum lapathifolium and P. muhlenbergii) , and from a yellow dock 

 (Rumex patientia or brittanicus) . The writer has taken it on 

 P. lapathifolium, on bindweed or wild buckwheat (P. convolvulus), 

 on sheep sorrel (Rumex aceioseUa), on curly dock (R. crispus), bitter 

 dock (R. obtusifolius), and willow dock (R. salicifolius) . It was also 



found by Chittenden and 

 Titus (34) feeding on the 

 leaves of the sugar beet 

 (Chenopodiaccese) . in a field 

 where it had evidently con- 

 sumed all of the dock and was 

 forced by hunger to feed on 

 this plant. The common 

 cultivated buckwheat and 

 rhubarb belong to the Polygo- 

 nacese and may very well be 

 food plants of this insect, 

 though it has never been re- 

 corded from them and the 

 writer has not had the oppor- 

 tunity of testing them. 1 



Several European writers 

 have recorded a number of 

 plants, not belonging to the buckwheat family, as food plants, but most 

 of these are doubtful. Brischke (21) mentions loosestrife (Lythrum 

 salicaria), and the common pansy (Viola tricolor). He was probably 

 mistaken about the latter, in view of the fact that the larva? of several 

 related sawfhes are known to feed on both the pansy and the violet. 

 Kaltenbach (14) mentions goose-foot (Chenopodium album) and La- 

 boulbene (16) mentions a reed (Arundo phragmitcs), but a careful 

 reading of their papers shows that they merely found the prepupal 

 larvae in the stems of these plants, which does not necessarily indicate 

 that they aie food plants, as the full-grown larva will bore into any 

 suitable stems, or even rotten wood or soft bark. Kleine (35) found 



Fig. 1. — The dock false-worm (AmeiasUgia glabrata): a, 

 Larva in hibernation cell in stalk of the dock plant; 

 o, pupa of dock false-worm in larval hibernation cell. 

 Enlarged. (Original.) 



iln the summer of 1916, leaves of the common rhubarb and those of a wild species of Eriogonum were 

 tested as food for the false-worm larvae. A number of larva? of different ages were provided with these 

 leaves, and fresh food was supplied daily. The larvce fed to some extent, bur in a few days all had 

 died, and it seems apparent that the leaves of these plants do not form a suitable food for this insect. 



