THE CANADIAN ENTOMOLOGIST 309 



OBSERVATIONS ON LECANIUM CORNI BOUCHE, and 

 PHYSOKERMES PICEM Schr.* 



BY F. A. FENTON, COLUMBUS, O. 



The following studies on the life history and habits of two 

 of our common soft scale insects were made at Madison^ Wis- 

 consin, under the direction of Prof. J. G. Sanders. The writer 

 is greatly indebted to Professor Sanders for invaluable assistance 

 and to Mr. A. A. Girault for the determination of parasites. 



The European Fruit Lecanium {Lecanium corni Bouche). 



Lecanium corni, probably native of Europe and one of our 

 commonest and most widely distributed soft scales, has been the 

 subject of much discussion in various scientific and popular journals. 

 Sanders^ has demonstrated that it is capable of much variation 

 in form, size, and coloration even on the same host, and since it 

 develops on numerous plants it is especially subject to a variety 

 of normal environmental conditions. For instance, on hickory the 

 ovipositing females are almost invariably white with black mark- 

 ings (Plate XV, fig. 2b), instead of the normal brown coloured forms 

 (Plate XV, fig. 2a) . Parasitism and disease produce abnormally de- 

 veloped forms, and these as well as immature individuals have 

 been described as separate and distinct species. 



History. — This insect was first reported in this country in 

 1851 when Fitch described it as Lecanium tilicB^. In 1859 it was 

 found in Canada and in the United States as far west as Minne- 

 sota^, and in 1891 Crawford found it in large numbers in Cali- 

 fornia^. Until 1908 there was much confusion regarding the 

 identity of this species as its numerous synonyms indicate. It was 

 found, however, that while external appearances might be ex- 

 tremely variable, certain microscopical characters remained con- 

 stant, and Marchal^ and Sanders^ reduced to synonymy some forty 

 so-called species, the form described by Bouche in 1844 as Lecanium 

 corni having priority. 



*Contributions from Entomological Department, University of Wisconsin. 



1. Sanders, Jour. Ec. Ent., Vol. II, I^o. 6, pp. 44.3-445, 1909. 



2. Fitch, 4th. Rep. Reg. Univ., N.Y., p. 69, 1859. 



3. Fitch, 3rd Rep. Ins., N.Y., p. 50, 1859. 



4. Crawford, Rep. Calif. Bd. Hort, p. 12, 1891. 



5.. Marchal, Ann. Soc. Ent. Fr., LXVII, p. 264, 1908. 

 6. Sanders, loc. cit. 

 September, 1917 



