424 The Ohio Naturalist. [Vol. IX, No. 3^ 



species, in only one or two instances has anything like a definite 

 life history been worked out and then not very completely. 

 Reports of their occurrence, the extent of injury and occasionally 

 a description of egg, larva or pupa, with a few recommendations 

 for treatment make up the bulk of the limited amount of liter- 

 ature available. Mr. F. H. Chittenden^ of the Bureau of Ento- 

 mology has worked out the life history of Disonycha xanthome- 

 laena at Washington, D. C. Miss M. E. Murtfeldt^ reported the 

 same species as doing considerable damage to spinach beds in 

 Missouri in 1S99. Mr. L. Bruner® has reported D. quinquevittata 

 and D. pensylvanica as injurious to young trees in Nebraska, 

 early in the spring when the buds begin to open. Mr. H. 

 Garman^ has reported D. glabrata from Lexington, Ky. where 

 the larvae strip the leaves from pigweed, Amarantus retro flexus. 



D. triangularis and D. xanthomelaena also do a considerable 

 amount of injury to beet leaves in Illinois, although the natural 

 host plant is the lambs-quarter. Brief mention of some of the 

 other species has been made at various times, a list of which 

 literatui:e is found in the appended bibliography. 



Of the 18 species in the genus, 11 are found in Ohio, the list 

 of which is as follows: 



1. Disonycha pensylvanica. 7. Disonycha abbreviata. 



2. " discoidea. 8. " triangularis. 



3. " quinquevittata. 9. '' xanthomelaena. 



4. " crenicollis. (collaris.) 



5. " caroliniana. 10. " mellicollis. 



6. " dabrata. 11. " collata. 



to' 



A complete key and quite elaborate descriptions of all the 18 

 species of the genus has been w^orked out b}^ Mr. Geo. H. Horn, 

 M. D., and included in his paper on "A Synopsis of the Halticini 

 of Boreal America" and since no key for the distinctly Ohio 

 species is in print, the following key, adapted in great part from 

 Horn, is presented with brief descriptions and notes on the 

 distribution of the several Ohio species. 



Key to the Ohio Species of Disonycha. 



After Geo. H. Horn, M. D. 



1. Form elongate, parallel, elytra subsulcate, thorax rather irregularly 



convex; elj'tra yellow, with black vittae pensylvanica. 



Varieties: 



Thorax with spots confluent in a large discal black space, having 

 a comparatively narrow yellow border. Body beneath and legs 



black ' limbicollis. 



Head in part yellow. Thorax beneath entirely yellow. Body 



beneath black, abdomen paler at sides and apex., .pensylvanica 



Head in part yellow. Thorax beneath entirely yellow. Body 



beneath black. Abdomen paler at sides and apex. Legs are 



reddish yellow, tibia darker, tarsi piceous pallipes. 



Black of the surface replaced by a rufous; legs even to tarsi, 



reddish yellow conjugata. 



Form more or less oval, elytra even; thorax regularly convex 2 



