habits of Chironomus (Ortkocladms) sordideUus. 523 



Its colour, which is bright red, 

 renders the mite conspicuous 

 even through the wall of the 

 tube. The mite does not appear 

 to do any injury to its host, 

 even when, as sometimes occurs, 

 two are present on the same 

 pupa. It has not been seen 

 upon the larva. When the pupa 

 is extricating itself from its 

 chamber, the mite occasionally 

 becomes dislodged, and is left 

 behind, evidently ill at ease, as 

 its agitated movements show. 

 Generally, however, the mite is 

 carried up to the surface of the 

 water together with the pupa 

 itself. And then an unexpected 

 thing happens. One might 

 imagine that when the fly 

 emerges, the mite Avould remain 

 attaclied to the pupal skin ; but 

 such is not the case. When the 

 pupa rises to the surface, the 

 mite is apparently aware of what 

 is going on, and, all alert, at the 

 very moment when the old skin 

 cracks, it releases its hold and 

 transfers itself to the body of 

 the half-extricated fly. It is 

 interesting to watch the mite, 

 hitherto perfectly passive, exe- 

 cute this rapid and sudden move- 

 ment. Thus when the fly leaves 

 the water and rises into the air, 

 the mite, still a six-legged larva, 

 is borne along with it. The 

 ultimate fate of the mite can 

 only be guessed at. 



My best thanks are due to 

 Professor Miall for his valuable 

 assistance during the preparation 

 of this note. 



iM. 



Fig. 2. Pupal tube of Chirono- 

 mus {Orthodadms) 

 sordideUus x 8. 



