AOfi 22 19U3 



PSYCH K. 



NOTES ON THE IMMATURE STAGES OF SOME TINGITIDS OF 

 THE GENUS CORYTHUCA. Plate 3. 



BY AUSTIN W. MORRILL, PH. D., ENTOMOLOGICAL LABORATORY, MASSACHUSETTS 

 AGRICULTURAL COLLEGE, AMHERST, MASS. 



The study of these insects by the writer was begun as a consequence of 

 noting the marked difference vvhicli was evident between the eggs of the oak- 

 inhabiting TiNGis of this locality and the eggs figured in Comstock's Manual for 

 the Study of Insects as those of Corythuca arcuata. Later it was found that the 

 young of the Buttonwood Tingis {Corythuca ciliata) so closely resemble those of 

 the Oak Tingis as to make their distinction possible only by microscopic examina- 

 tion. Say's description of Corythuca arcuata covers several closely allied forms 

 which may be considered species in the process of formation. Others which are 

 recognized as distinct species appear to be very closely allied ; at least in their 

 adult condition. The differences, which are noted in this paper, in the immature 

 stages of the Oak, Hawthorn, and Buttonwood tingitids indicate that the relation- 

 ships of these perplexing forms will be better understood when the egg and nymph 

 stages of each have been studied. 



Description of the Immature Stages of the Oak Tingis, Corythuca 



arcuata Say. 



Egg (Plate 3, figs. I and 2) : subelliptical in outline, basal end rather pointed, apical 

 end capped with a narrow cylindrical collar or band surmounted by a low pyramid with 

 from fifteen to twenty ridges extending from the base to the apex. From the apex of this 

 pyramid there usually arises a slender filament which is variable in length but as a rule about 

 one fifth as long as the egg. Below the collar the ^2,% is evenly covered with a thin layer 

 of wax, jet black in color, and rough, resembling sand paper under low power objectives. 

 This outer wax covering may be easily rubbed off, disclosing the smooth shiny black Q.g^ 

 chorion. The pyramidal portion of the apical cap may be either whitish or black. The 

 length of the ^^^, not including the apical filament, is about .56 mm., its greatest width 

 about .24 mm. 



For the purpose of simplifying the following description of the nymphs I will 

 designate the three principal types of spines found in the nymph stages as follows: 



