At-U 



Article I. — Sfm/ifs of the Life Ilisfor//. ILtbifs, (oid Taxo- 

 1101)1 ic h'r/dfioiis (if a Ncir iSpcries of Olicrcd ( Olx'ird iihiiicoln 

 Cliiifcndcii). By F. M. Webster. 



The species of this genus of ('('rdiiihijvidir are not easy to 

 define, on account of their variability' in color, and they have 

 for this reason been the subject of re|ieated and radical revision 

 by entomologists. In 1878, Dr. G. H. Horn, in his revision of the 

 genus* restricted the number of species to eleven, while Mr. Chas. 

 W. Leng, eighteen years later, reduced this number to five. In 

 this latter revision Ohcrca frlpiniddfa Swederus was divided in- 

 to two groups, or forms as they are there called, the bliiiiii-ulnfd 

 form and the fripiincf(if<i form, the species itself being thus 

 burdened with no less than eleven synonyms. Even this ar- 

 rangement is unsatisfactory, and considerable evidence has ac- 

 cumulated tendingto show thatwe may have species the adults 

 of which are difficult to separate, whose larvcB are restricted to 

 very different food plants. Thus Ohcren hhiKicuUda has hitherto 

 been reared exclusively from plants belonging to the genus 

 Hiihiis, while 0. fripiiiuiata breeds in a variety of food plants 

 other than Riihiis, and including the elm. It is therefore inter- 

 esting to find another apparently valid species which seems re- 

 stricted to the elm. although O. fi'iiiin/cfdfn, as at present under- 

 stood, breeds on the same tree with the one under consideration. 



One of its close allies, Ohcrcfi fc.nnin. is a southern form, 

 while O. iihiiici)hi has thus far been found only in a single city 

 of about 20.000 inhal)itants in central Illinois. Even there it 

 does not infest the elms of the entire city, l)ut has confined it- 

 self to a certain section, within which it is so excessively abun- 

 dant that the females are compelled to deposit their eggs in the 

 same twigs again and again, notwithstanding the fact that only 



*Trans. Am. Ent. Soc, Vol. VII., pp. 45-48. 

 '\Loc.cit., \'ol. XXIII., pp. 153-157. 



