Vol. XXV] ENTOMOLOGICAL NEWS III 



Species Limits in the Genus Lucilia (Dipt.). 



By CHARLES H. T. TOWNSEND, Lima, Peru. 



The paper by Mr. John D. Tothill on variation in North 

 American Lucilia spp. (Ann. Ent. Soc. Am., vol. 6, pp. 241-25') ) 

 is excellent so far as it goes. The number of specimens ex- 

 amined is pitifully small. Until work of this general nature, 

 but on a much more extended scale, has been done and verified 

 for any given group of muscoid species, we shall not know 

 what are the species limits within that group. It is quite pos- 

 sible that the ten species of Lucilia in question are largely 

 variations of previously described species, but the evidence 

 presented is not conclusive in all the cases. The results de- 

 duced from the rearings of L. sericata carry a certain slight 

 amount of weight ; the others mean almost nothing. 



The isolation of any form by means of a name and descrip- 

 tion becomes at once a challenge to all interested to test the 

 form in question and determine its standing. Such work is 

 perfectly legitimate, but it must be done with care and full at- 

 tention to details in order to exclude possible sources of error. 

 The capacity for exact results of the plan followed in the 

 above paper is very questionable. An isolated egg-mass, not 

 followed through its entire deposition, carries no positive as- 

 surance of all the eggs therein being the product of a single 

 female fly. If left undisturbed, the female of Lucilia usually 

 deposits at one sitting the entire matured product of both 

 ovaries, which is to say one egg from each ovariole. But this 

 takes considerable time and the flies may easily be disturbed 

 from a variety of causes, resulting in a partial deposition by 

 one female, which is added to by another. The writer has 

 noted hundreds of thousands of eggs deposited by Lucilia fe- 

 males in continuous masses, often plastered over each other 

 tier upon tier, which showed no line of separation between the 

 products of different females. The only safe plan to pursue 

 in this work is to rear adults from puparia, mate like individ- 

 uals, isolate the gravid females and furnish them proper food 

 materials for oviposition, rear the progeny, mate these again 

 similarly, rear their progeny, etc. Every specimen in the en- 



