82 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



of Acdes fuscus O. S. In fact, we are able to detect in our 

 specimen of pallidohirta the white lateral line on the abdomen 

 characteristic of fuscus. 



It is probable that this silvery scaling may occur on other 

 parts than the abdomen, for instance on the legs, in which case 

 Acdes nivitarsis Coq. will be seen to be only an aberration of 

 Acdes canadensis Theob., as Dr. Ludlow formerly suggested 

 to us. 



We are ignorant of the cause of this peculiar variation. It 

 cannot be produced by the fluid in which the specimens were 

 preserved, because the males of calopns from Spain, preserved 

 in the same bottle with the females, were not thus affected, 

 and because Mr. Grossbeck's type of pallidohirta was not put 

 in fluid. It cannot be due to the specimens having been wet 

 on emergence in the breeding jar, because the specimens from 

 Spain were not bred, but captured, some having blood in their 

 stomachs. It seems doubtful whether the chemical contents of 

 the water is the cause, for while pallidohirta and n in' tarsi's 

 both came from pools on the mountains of New Jersey, the 

 aberrant calopns could only have bred in water-vats or other 

 artificial receptacles in Malaga, Spain. Moreover, normal exam- 

 ples of canadensis were bred from the same pools as \.\\z pallido- 

 hirta, at the same time, as Mr. Grossbeck states, and these 

 should have been similarly affected if the composition of the 

 water were the cause. 



We can only suggest the action of cold upon the newly formed 

 pupa?. W. H. Edwards and others have shown that the 

 effect of cold upon the newly formed pupa? of Lepidoptera is 

 to produce a suffusion of the colors, the light colors being 

 extended and enlarged at the expense of the dark ones, as in the 

 peculiar form calverleyi of Papilio asterias. The similar suf- 

 fusion of the white abdominal or tarsal bands of the Acdes 

 might produce the peculiar effect noted. That this is a possi- 

 ble explanation is supported by the facts that the calopns from 

 Spain were taken in December, while the New Jersey insects 

 were bred from early pupae in the spring of 1905. The writers 

 have cause to remember the late snows and cold of that spring, 

 which hampered them in their collections of the early mosquito 

 larvae in Massachusetts and northern New York. That the 

 Aedes canadensis in the same pool were not similarly affected 

 by the cold, as were the fuscus into a pallidohirta form, may be 

 explained by their having pupated later, after the cold spell. 

 Mr. Grossbeck states that they emerged later than \btpallido- 

 htrta. 



