100 Proceedings of the Royal Physical Society. 



XII. — Note on " Leptus phalangii " and " Leptus autumnalis," and 



their parent Earth-mites. By William Evans, F.R.S.E. 



(Read 28tli February 1910. Received 3rd March 1910.) 



The minute hexapods known as harvest-bugs, to which the generic name 

 of Leptus has long been applied, are generally, and no doubt rightly, recognised 

 as the first or larval stage of mites belonging to the Trombidium group. 

 Kegarding the particular adult form to which each belongs, much un- 

 certainty, however, exists. As a slight contribution to the subject, the 

 following results of some observations made by me in this district during 

 the summers of 1908 and 1909 may, therefore, be worth recording. 



Rhyncholophus {Ritteria) nemorum, Koch : — To this species Dr C. F. George 

 refers a brown Khyncholophid mite which I have found rather commonly 

 among moss and fallen leaves, and also under stones, in widely scattered 

 localities around Edinburgh. There appears to be some doubt as to the 

 identity of Koch's Rh. nemorum; and Dr Sig Thor, in his paper on Norwegian 

 Rhyncholophidae (1900), places it with a ? under Ritteria vertex, Kramer. 1 



On 31st July 1908 I got, at Crosswood Eeservoir in the south-west of 

 Midlothian, two Phalangids or " Harvest-men " (Fhalangium opilio) with 

 six and eight, respectively, of the little red larval ticks known as Leptus 

 phalangii adhering to their legs. Without disturbing the Lepti, the 

 Phalangids were put into a glass-topped box containing a layer of fresh earth. 

 Next day three of the parasites left their hosts, and within a week all had 

 dropped off, and entering the earth went to rest just beneath the surface. 

 There they underwent a developmental change, and in the beginning of 

 September (3rd and following few days) nine emerged as Khyncholophid 

 mites which, though immature, were to all appearance of the same species 

 as my Ritteria nemorum specimens ; this Dr George has no hesitation in 

 saying they are. Unfortunately none of these " nymphs " reached maturity 

 although some of them remained alive for several weeks. 



Trombidium holosericeum (L.) Fab. : — On 24th April 1909 several 

 examples of this beautiful scarlet mite, which is also common and widely 

 distributed in this district, were taken ou Largo Links, Fife. Two females 

 were placed in a glass tube along with some sprays of moss. There, in the 

 end of May (27th, etc.), they deposited about 300 red eggs in clusters of 

 20-40. Hatching started on 8th July, and in the course of the next four 



1 I liave since submitted specimens (including one of the nymphs reared from 

 L. phalangii) to Dr Sig Thor. He agrees in designating them for the present Bhyncholophus 

 (Ititteria) nemorum, Koch, but indicates that this may be a " Collektiv-name " for more 

 than one species. I hope to hear from him again when he has had time to prepare 

 dissections of the specimens, and study the whole subject more closely (22 iv. 10). 



