220 EXTOMOLOGicAi, NEWS. [June. "l8 



is made of hardened earth or clay, and the final molt may 

 become mechanically dependent on this factor and impossible 

 without it. In a later stage, when the insects have adapted 

 themselves to a new environment, no cocoon is formed, but 

 pupation takes place as if there were a cocoon surrounding 

 the pupating larva; the larval skin cannot be successfully shed, 

 and the result is a puparium, but the latter, consisting of both 

 larval and pupal skin, is opened after the fashion of a cocoon. 



Literature. 

 Brauer, F., 1883. Die Zweifluegler cles K. K. Hofmuseums zu Wien, 



Denkschriften der Wiener Akademie der Wissenchaften. 

 Berling, Th., 1882. Beitrag zur Metamorphose zweifluegeliger Insek- 



ten. Archiv fuer Naturgeschichte, Jahrg. 48, Heft 2. pp. 225- 



226. 

 Malloch, John R., 1917. A Preliminary Classification of Diptera, 



Exclusive of Pupipara, Based upon larval and pupal character:-, 



with keys to imagines in certain families. Part I., Bull. 111.. Lab. 



of Nat. Hist., Vol. XH, Article HL PP- 403-407 (Dolichopodidae). 



March. 



Psyllidae of the vicinity of Washington, D. C, with 

 description of a New Species of Aphalara (Horn.) 

 By W. L. McAtee, Washington, D. C. 

 The list of species herein presented comprises the psyllids 

 recorded from the District of Columbia region in the papers 

 cited in the bibliography plus those obtained by the writer 

 and other collectors whose names are mentioned in connection 

 with their captures. The list totals 23 species, and may be 

 compared with those for the vicinity of Ames, lowa.^ 15 spe- 

 cies, of which 4 were described as new ; for New Jersey,* 

 18 species, of which one is cited merely as n. sp. and 3 are 

 recorded on hypothetical grounds ; and for Colorado, 18 spe- 

 cies, 14 of them, cited under manuscript names. ^ 



Of the 23 species here listed 5 were originally described 

 from material obtained wholly or in part from the vicinity of 



iMall}', C. W. Proc. Iowa Ac. Sci. 1894 (1895), pp. 152-171. 

 2Smith, J. B. Rep. N. J. State Mus. 1909 (1910) pp. 108-110. 

 ^Gillette, C. P. and Baker, C. F. Bui. 31, Colo. Agr. Exp. Sta., 1895, 

 pp. 113-115- 



