310 



ficieutly acquainted with the distinguishing characters between the 

 young hirvai of Hypoderma lineata and the other species at the time 

 when the doubtful determination was made, and am now inclined to 

 believe that the specimen was a partly developed larva (third stage) 

 of Hypoderma lineata j as the Qgg or larva of this species is much more 

 likely to have been swallowed in milk than that of H. diana^ which 

 infests deer.* 



An interesting letter called forth from tlie above experience has al- 

 ready been published on p. 275 of this volume of Insect Life from 

 Prof. W. M. Schoyen, Government Entomologist, Christiania, Norway, 

 referring to a communication of his own on the occurrence of Dipterous 

 bots under the skin of man, from which I reproduce the following: 



As pointed out hi this article, we know of cases of traveling grubs under the human 

 skin in some districts of our country from over one hundred years ago up to the present 

 time. Many of these grubs I have myself seen and examined, and they were all of 

 the Hypoderma larvse {sine dubio — Syp. ionis), and, as a rule, they have accomplished 

 longer ramblings under the skin, always in an upward direction, previously to their 

 appearance, through an opening in a tumor on the upper part of the body (head, neck, 

 shoulders, etc.)- All of them have lived in this manner for months, and came out in 

 course of the winter months (February, etc.), but were always still much too young 

 to go through their transformations. However, I have no doubt at all that they 

 belong to Ri/podcnna bovis, as it is especially with persons who look after or take care 

 of cattle in the summer mouths that such grubs are to be found during the winter. 

 It is evidently the smell of cattle which attracts the bot-fly to them. Htipoderma 

 diana does not occur in our country. 



The article maybe found in the EntomoIo</isk Tidski-ift, Stockholm, vol. vii (1886), 

 pp. 171-187, and contains also a short historic r^sum6 of all accidents of this kind 

 observed up to that time, which have been published here in Norway and elsewhere. 



DIFFERENCES BETWEEN THE LARV^ OF H. BOVIS AND H. LINEATA. 



Dr. Brauer has devised a very convenient and original method of 

 showing diagrammatically the spiny armature of the larvae of Hypoderma 

 by means of which the dorsal and ventral surfaces as well as the three 

 rows of lateral protuberances are shown together, so that different spe- 

 cies may be readily compared. 



I reproduce his diagrams (Figs. 45 and 40) of the larvse of horis and 

 lineata {boiiassi)^ together with his table for distinguishing the larvae of 

 the two siiecies. 



In the diagrams and table the first two joints are considered as 

 cephalic and marked 1, since, as Brauer observes, this is necessary 

 for comparison with described larvae which as a rule have been consid- 

 ered to have but eleven segments. The wide spaces represent the dor- 



* Eeexamination of the specimens which I have been able to make through the 

 kindness of Dr. Freeman, since the above was written, shows that this supposition 

 is correct, and that the larva is undoubtedly that of lineata, and is of the second 

 subcutaneous or third larval stage — the spiny areas and other characteristics agree- 

 ing exactly with this stage. 



The known habits of this larva render this determination doubly sure, and indicate 

 that the penetration to the surface may, under uufavoraltle or unnatural conditions, 

 be delayed iintil the second subcutaneous stage is assumed. 



