726 



ARTHROPODA 



is commonly found in the South of England during August and 

 September. It is also common in France during the hot and dry 

 months. Bruyant raised a nymph in 1910 which was thought at 

 first to be M. pusillum Hermann, but this is now thought to be 

 doubtful. It is also found in Germany. It generally attacks small 

 mammals, such as dogs and cats, Acarus hatatus Linnaeus of 

 Surinam perhaps belongs here. M. wichmanni Oudemans is found 

 in New Guinea and Celebes. 



Microtrombidium akamushi Brumpt, 1910. 



Synonyms. — Akamushi (red mite); Kedani (hairy mite); Shashitsu 

 (sand mite); Shimamushi (island mite); Tsutsugamushi (dangerous 

 mite); Yochuhia. 



Definition. — Microtrombidium of various characters, probably 

 covering several distinct species, with and without all dorsal hairs 

 of the palp feathered. Hair on galea of maxilla always strongly 

 feathered. Hairs on dorsum of palp not feathered, except that on 

 the tibia. Tarsal claw trifurcate. Last tarsus without long fine 

 tactile hair. 



Remarks.— The form shown in Fig. 342 may be a distinct species 

 from M. akamushi, because all the dorsal hairs on the palp are 

 feathered. This may be called Microtrombidium brumpti Hirst, 



These are the mites which cause Japanese river fever, called 

 tsutsugamushi fever. 



Morphology.— The larva is orange red in colour, o-i6-o-24 milH- 

 metre in length, by o-i 0-0-24 millimetre in breadth. The palpi 

 are leg-like, and the body and legs are veiy hirsute. 



The scutum is oblong, not wide, with straight posterior margin and 

 usually seven hairs. The pseudostigmata are nearer the posterior 

 than the anterior margin. 



Eyes are well developed. 



Dorsal hairs are 2, 8, 6, 8-10, 8, with a few posterior hairs. 



The first coxa has two hairs. The hair on the galea of the maxilla 

 is strongly feathered, while those on the dorsal surface of the palp 

 are plain, except the one on the tibia, which is feathered. Tarsus 

 with seven feathered hairs and a blunt rod-like hair. Legs slender 

 and moderately long, with strongly feathered hairs. 



Life-History. — -The akamushi does not attack insects nor spiders, 

 but will attach itself to man and to small mammals — monkey, dog, 

 cat, rat, mouse, rabbit, and guinea-pig. 



The mite remains on its host for three to four days, during which 

 it swells up and turns pale. It then drops off and finds shelter 

 under the ground, where a metamorphosis takes place in some five 

 to six days, during which a nymph forms under the larval skin, and 

 from which it escapes. 



The newly hatched nymph, 0-4-0-57 xo-25-0'285 mm., is a minute 

 eight-legged creature, which, though it crawls about, is neither para- 

 sitic nor predaceous, but it feeds upon the juice of potatoes, melons, 



