486 THE ANIMAL PARASITES OF MAN 



indeed, as many as three species come under consideration : T. gymnopterosum, 

 L., T. fuliginosum, Herm. (according to Brucker), and two species known hitherto 

 only in the early stage, T. striaticeps, Helm, et Oudem., and T. poriceps, Helm, et 

 Oudem., which are not only parasitic on mammals, but on birds, on Arthropods and 

 especially' on insects. Arthropods appear to be the normal hosts for the larvae. 



The above-mentioned forms invade the skin of man by means 

 of their oral apparatus, by preference invading the orifices of the 

 sebaceous glands so as to suck the blood ; around the point attacked 

 there arises a wheal about the size of a lentil, and around the inserted 

 hypopharynx a fibrinous secretion, the " proboscis," which, however, 

 is a product of the host, just as chitinous secretions are provoked by 

 Trombidia parasitic on Arthropods. 



Further species, analogous in habit to Leptus autumnalis, are described by Riley 

 from Central and South America as L. americanus and L. irritans. 



[L. autumnalis attacks small mammals by preference, such as moles 

 and hares, which are often literally covered with them. Dogs are 

 also subject to their attack, and cats suffer similarly. This mite also 

 frequently appears in colonies on cows ; cavalry horses after autumn 

 manoeuvres often suffer from an erythematous affection about the 

 hocks and knees due to this pest. 



[A number of Leptus, so far undescribed, occur abroad which 

 attack man in the same way as L. autumnalis in Europe. Dr. Durham 

 has brought me specimens from British Guiana called bete rouge ; 

 this species works under the skin much as does our European species, 

 but it is very distinct, being considerably larger. F. V. T.] 



Trombidium tlalsahuate, Lemaire, 1867. 



T. tlalsahuate occurs in Mexico under conditions similar to those 

 of Leptus here. It also frequently attacks men, and especially fastens 

 itself on to the eyelids, in the axillae, navel, or on the prepuce ; it 

 induces itching and swelling of the parts affected, and sometimes 

 even causes suppuration ; the symptoms, however, generally disappear 

 after a week and remain localized. 1 



Other species of mites which attack man are reported, mostly 

 by travellers, from various other places ; zoologically, however, 

 there is little known about them. The pou d'agouti in Guiana, 

 niaibi in New Granada, colorada in Cuba, mouqui in Para, and the 

 buschmucker in New Guinea represent a few of these. 



1 Lemaire, "Import, en France du tlalsahuate," Compt. vend. Acad. Sci., Paris, 1867, 

 Ixv, p. 215. 



