LEPTUS AUTUMNALIS 351 



many parasitic forms are provided with pedunculated suckers [ambu- 

 lacra, F. V. T.]. Respiratory organs (tracheal tufts) may be present or 

 absent. The nervous system is reduced to a minimum, eyes are usually 

 lacking. The intestine, situated in the central part, generally has three 

 blind appendages ; the anus is situated on the venter above the pos- 

 terior end. Sexes separated ; nearly all the species deposit eggs, from 

 which six-legged larvae hatch. The acarina live either free in the water 

 or in moist soil, or they are parasitic on plants and animals. 1 



I. Fam. Trombidiidce (Running Mites). 



Soft-skinned acarina with tracheae and with two eyes, usually peduncu- 

 lated ; they are often brightly coloured ; chelicerae lancet- or claw- shaped ; 

 pedipalpi claw-like ; legs composed of six segments, with suctorial discs 

 between the terminal ungues.- Larvae six-legged. 



Leptus autumnalis, Shaw, 1790. 



This name is used for the larvae of mites ' which are found 

 towards the end of summer on grass plots, bushes and cereals, 3 

 and which have a predilection for attacking mammals and human 

 beings (Harvest-mites, Autumn-mites, Grass-mites, Rouget, Bete- 

 rouge, Aoutat, Red bug). To all appearances these are the larvae of 

 at least two species, the corresponding adult forms of which have 

 certainly long been known, but have hitherto not been definitely 

 traced from these larvae. P. Megnin, in 1876, asserted that 

 Leptus autumnalis was the larval form of Trombidium holosericeum, 

 a red-coloured species of mite which is frequently found on trees, 

 on the earth, &c., in the spring ; and which in June and July 

 deposits eggs from which reddish larvae, 0*23 mm. in length, 

 and 0-19 mm. in breadth, hatch out. 4 As, however, Moniez 



1 [Acarina are also found living upon trees feeding upon other Arthropods and 

 also upon spores of lichen and fungi (Oribatida or Beetle Mites) ; they also swarm 

 indoors amongst stores and provisions (Tyroglyphidce and Glyciphagi, Household, Sugar 

 and Cheese mites). F. V. T.] 



2 [Some have seven segments to the legs. F. V. T.] 



3 [This minute parasite is especially obnoxious in barley fields. In walking across 

 barley stubble one is sure to be attacked by this parasite in the autumn in many 

 districts. This Leptus attacks poultry also when turned out on to the stubble fields 

 in autumn, but does not do much harm. F. V. T.] 



4 [This mite occurs chiefly in gardens, and is often very prevalent amongst rows 

 of peas. In the spring it may frequently be found on fruit trees. In barley fields, 

 where Leptus autumnalis is most abundant, I have often found traces of Holosericeum 

 early in the year. Nut pickers are frequently attacked by this Leptus, and also 

 pickers in fruit plantations. F. V. T.] 



