254 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



favorite, but Smartweed is liked above all. Indeed, the black bindweed 

 {Polygonum convolvulus^ L.), which is very common in Minnesota, where 

 it is olten called wild buckv/heat, is so universally preferred by the locusts 

 that some farmers have thought seriously of cultivating it around their 

 fields as a lure, to draw the insects off from the cultivated crops and 

 thus facilitate the killing of the ])es^s. Among the wild plants least 

 liked may be mentioned Cocklebur, Heliauthus, and Purslane, but more 

 particularly the milkweeds {Asclepias) and the Dogbane (Apocynum), 

 An occasional Salvia tricJiostemmoides and Ve7'nonia novwhoracensis were 

 also left untouched in the general ruin by the young insects in Missouri in 

 1875. But the plant of all others that is exempt from the attacks of these 

 ravenous ereatures is a low, creeping glossy-leaved herb for some time 

 known to botanists as the Amarantus blitum and supposed to have been 

 introduced from Europe. Mr. Sereno Watson has, however, lately 

 described it by the name of A. ( Pyxidium) hlitoides,'^ and it is common 

 and indigenous to the valleys and plains of the interior from Mexico to 

 Northern Nevada. It is fast spreading eastward. 



Mr. Eiley found this plant unmolested in Missouri *'even where the 

 insects were so hard pushed for food that they were feeding on each 

 other and on dead leaves, the bark of trees, lint of fences, &c., and 

 where they were so thick hiding amid its leaves that fifty to a hundred 

 occurred to the square foot." 



The dislike these insects show for leguminous plants is well known, and 

 a crop of peas will often succeed where they abound, when all else is 

 ruined. This is the case alike in Texas and British America, for Mr. J. 

 G. Kittson, of Fort Walsh, N. W. T., writes of his experience in 1877 : 

 " Peas are the last vegetable the locust will touch. In Swan Eiver the 

 Mounted Police garden had a large patch of peas in rows, and only the 

 outer three rows were damaged, and this was only when the insect had 

 attained its full growth and there was nothing else to feed them." Mr. 

 G. M. Dawson has wisely suggested that this dislike may afford an ex- 

 planation, on Darwinian grounds, of the prevalence of such plants on 

 the Northwestern plains. 



To sum up, where the insects are abundant, the prairie-grass, the wild 

 weeds mentioned as disliked, and the leaves of most of the forest-trees 

 generally remain green; but the little Amarantus is the only plant 

 which we'^have so far found proof against the insects under all circum- 

 stances. A marked preference is always shown for plants that are un- 

 healthy or wilted, and a dislike for those in low, wet, or marshy places. 



In coneluding these notes on the food- habits of locusts, we will briefly 

 refer to a rather prevalent belief that the newly hatched-lccu>ts live for 

 many days on dew. The belief has originated independently in different 

 parts of the world, is mentioned by Anacreon and Hesiod, and perpet- 

 uated by later poets. It is doubtless due to the facts that, if the 

 weather be cool, the young insects huddle together and can live for 



^0 Proc. Am. Ac. Sc. & Arts, Vol. XII, p. 273. 



