No.509] ECOLOGY OF INDIAN CORN PLANT 297 



i ( lirysomelida?) but to different genera ( ( 'olaspis, Graph- 

 ops and Typophorus), and to species native in the 

 United States, are all so closely adapted to underground 

 life and to the root-feeding habit that they are distin- 

 guishable from one another only by rather slight and in- 

 conspicuous characters. They are often associated in 

 large numbers in the same fields, living wholly on the roots 

 of strawberry plants, which they affect in an identical 

 manner, so that from the appearance of the injury itself 

 one could not possibly tell which of the three species was 

 present in the field. One of these root-worms, the 

 (/olaspis larva, feeds also on the roots of other plants, 

 especially on those of timothy and corn, but the two other 

 larvae have been found only among strawberry roots. 

 They seem thus to be strict competitors for food from 

 the same part of the same plant, and as their locomotive 



throughout the season, and each of these three insects, 

 having a short larval period, feeds on strawberry roots 

 for only a part of this growing season. It is an inter- 

 esting and striking fact that the life histories of the three 

 competing insects are so related that the larva' do not 

 infest the plant at the same time, but follow one another 

 in close succession, beginning early in May and ending: 

 late in the fall. The first of the species, the ('olaspis 

 larva, feeds from about May, to the end of June, the 

 Typophorus larva follows in duly and August, and the 

 Graphops larva begins in August and continues until tall. 



Consistently with this difference, the species concerned 

 hibernate in different stages of development -< \>lnsp> ap 

 parently as an egg, Typophorus undoubtedly a> an adult, 

 and Graphops as a larva in its subterranean cell, horn 

 which adults emerge the following June to /ay their cgg> 

 in Julv. With such a distribution of then 

 of these three species is able to maintain 

 strawberry in numbers as large as would > 



If on the 

 ssible for 



