234 ENTOMOLOGICAL NEWS. [December, 



Jersey until the very last days of June so far as my observations 

 extended, and in the laboratory they continued to emerge from 

 cocoons collected at Jamaica, L. I., Cologne, Atlantic County, 

 N. J., and Woodbine, Cape May County. N. J., until Sept. ist. 



The moths copulate soon after emergence from the pupa, which 

 usually occurs before 8 a. m., and before ii a. m. the female is 

 ready to oviposit. Eggs are laid anywhere on the trunk, and 

 even on the lower branches and placed singly or in groups on 

 bare bark or in crevices as may happen. If fertilization does 

 not occur within 24 hours the females lay their eggs unfertilized 

 to get rid of them. I have found 500 fully developed brown 

 €§■§3 — i- ^•, chitinized — in a female two hours from the pupa and 

 fully 100 white or immature eggs; 600 eggs is, therefore, a pos- 

 sible number from a single female, though I believe that only 

 those eggs that are fully developed when the $ emerges are 

 laid. This means between 45 and 500 according to my observa- 

 tions. I have no direct observations on the length of the ^%^ 

 stage. Mr. J. V. D. Walker makes it 10 days from his field 

 notes. Dr. L. O. Howard says 7 or 8 days from their records 

 at Washington. The truth is probably between the extremes 

 given. 



The danger period in New Jersey during which trees need 

 protection from borers is between June 20th, better 15th, to Sep- 

 tember 15th, better 30th. In Canada the period of emergence 

 is in July, but the moths fly throughout October, hence protec- 

 tion must continue until frost. 



PHYSIOLOGICAL SPECIES. 



By T. D. A. COCKERELL. 



The editors ask for a short account of " physiological species," 

 and while I have nothing new to say on the subject at the present 

 time, it may not be amiss to oft'er a definition of the phrase. . 



It is assumed, on Darwinian grounds, that the raison d' etre of 

 species is that they severally occupy different places in the scheme 

 of nature and that the essential specific characters all have, or 

 have had, some utility to the organism, or are, or have been 

 correlated with those possessing utility. It does not follow that 

 a new specific character need be superior to an old one which it 

 replaces, provided that it enables the organism to occupy a vacant 



