26 



SCIENCE 



[N. S. Vol. XLIX. No. 1253 



phasis will appear to be placed on inspection, 

 the limitations of which have in very recent 

 years been recognized. 



The book is remarkably free from gram- 

 matical and typographical error. Further- 

 more, the good quality of paper, the large bold 

 type and the pleasing cover should make the 

 book a welcome addition to the library of the 

 dairyman, dairy inspector, milk examiner, 

 milk distributer, public health official and 

 others who are at all interested in the field 

 which the author has covered. 



Leo F. Eettger 



SPECIAL ARTICLES 



THE OVIPOSITION HABIT OF GASTROPHILUS 

 NASALIS L. 



In a short article recently published in the 

 Canadian Entomologist, Vol. L., No. 7, July, 

 1918, pp. 246-248, entitled " Note on Oviposi- 

 tion of Gasterophilus nasalis L.," Dr. C. H. 

 T. Townsend makes the statement that he has 

 observed this species darting at the muzzle of 

 a horse, leaving " whitish eggs with their 

 sharp bases penetrating and adhering in the 

 skin of the upper lip." Unfortunately for the 

 proof of this observation the eggs were lost, 

 but the author states that similar eggs were 

 dissected from the abdomen of the fly. In the 

 same note the author remarks that the egg of 

 nasalis "is practically the same size and shape 

 as that of intestinalis and that by reason of 

 the moderately pointed anal end it is capable 

 of penetrating tender skin." Dr. Townsend 

 concludes that the attachment of the eggs of 

 nasalis to the hairs of the host only happens 

 inadvertently when the i.j misses its true 

 mark, namely, the tender skin of the lips. 



It is not unlikely that Dr. Townsend may be 

 capable of distinguishing the eggs of G. 

 hcemorrhoidalis from those of the other two 

 species by reason of its black color, but it is 

 rather unfortunate that he should say that the 

 egg of G. nasalis is of the same size and shape 

 as that of G. intestinalis. The eggs are abso- 

 lutely distinct both as regards shape and at- 

 tachment to the hair, and the egg of G. nasalis 

 is certainly not adapted for the penetration of 

 the host's skin. 



Far from the deposition of the eggs of 

 G. nasalis on the hairs of the throat being 

 accidental, it has been my experience that this 

 is almost invariable. Occasionally, as many 

 as six to eight eggs have been found on a 

 single hair. The adult fly so tfar as I am 

 aware, has never been seen to strike at the 

 lips but always at the hairs of the skin be- 

 tween the mandibles and sometimes on the 

 hairs of the cheek. 



The eggs of all three species are transversely 

 striated, a fact to which Dr. Townsend prob- 

 ably refers when he remarks on the trans- 

 versely corrugated structure of the chorion of 

 the egg of G. nasalis. But to add that these 

 striations in the case of the latter egg serve to 

 retain the egg in the skin after it is inserted 

 is purely fictitious. It is midoubtedly true 

 that the stalked egg of G. hcemorrhoidalis 

 which is invariably found attached to the 

 short hairs of the lips, often appears to pene- 

 trate the skin. Repeated examination has 

 shown, however, that the clasping stalk may 

 sometimes enter the hair follicle and thus give 

 the impression that it is actually inserted in 

 the skin. 



In simiming up, it is my opinion that Dr. 

 Townsend has conceived of his ideas from ob- 

 servations that are quite inaccurate and that 

 in a more detailed study of the habits of bot- 

 flies he would find nasalis never " strikes " at 

 the lips of the horse, and certainly in my 

 experience it has never been known to oviposit 

 there. 



A. E. Cameron 



Univeksity of Saskatchewan 



SCIENCE 



A Weekly Journal devoted to the Advancement of 

 Science, publishing the official notices euid pro- 

 ceedings of the American Association for 

 the Advancement of Science 



Published every Friday by 



THE SCIENCE PRESS 



LANCASTER. PA. GARRISON. N. Y. 



NEW YORK. N. Y. 



Entered in the po«t-»ffice At LaDcatter, P«., as second class matter 



