as the}' occur on the under surface of the bodies of grasshoppers and 

 harvest spiders or ''daddy h)ng legs"' (Phalangiidie) and under the 

 wings of the house fly. Just what species of harvest mites are trouble- 

 some to man in the United States is not known, but one of them, 

 perhaps the commonest, is referred to in literature as ^^ Leptus''' irrltan>i 

 Riley.' 



SYMPTOMS AND MANNKR OF ATTACK. 



Soon after the harvest mite l)urrows under the human skin a small red 

 spot appears (evidently the mite itself gorged with human Ijlood), after 

 which the surrounding- surface becomes congested, the affected area 

 spreading until it is from less than a quarter to a half or three-fourths 

 of an inch in diameter. This congestion may manifest itself within 

 less than an hour after exposure or may not be apparent for twelve 



hours or so, the fever 

 being at its height usu- 

 ally on the second day. 

 The symptoms are ai)t 

 to ))e first noticed when 

 the sufferer has removed 

 his clothing at night, or 

 upon awakening from 

 sleep. It sometimes 

 happens that there is lit- 

 tle irritation until some 

 time after exposure, but 

 with most persons sus- 

 ceptible to the poison- 

 ous effects of these mites irritation is first experienced on the second da v. 

 The feverish appearance of the afflicted skin area varies according to 

 the .'-usceptibility of the person attacked. Children dwelling or sojourn- 

 ing in mite-infested localities suffer greatly from these pests, experienc- 



1 Riley, Poisonous Insects, Extr. Kef. Handb. INIed. Sci., \(A. V, 1887, p. 745. 



Leptus is a genus founded on the larval Tromljidium. For those who may 

 desire further information in regard to the structure of the adult, the following 

 paragraph is transcribed from "A Treatise on the Acarina or Mites," by Nathan 

 Banks (Proc. U. S. Nat. Mus., Vol. XXVIII, pp. .30, 31, 1904), together with a 

 figure illustrating a common species: 



The "harvest mites" * * * are recognized by the body being divided into two portions, the 

 anterior (cephalothorax) bearing the two anterior pairs of legs, tlie palpi, mouth parts, and eyes. 

 The posterior (abdomen) is much larger and bears the two posterior pairs of legs. The mandi- 

 bles are chelate, at least there is a distinct jaw or curved spine-like process. * * * The body is 

 covered with bristles, or feathered hairs, according to the species. The palpi are five jointed, 

 quite prominent, often swollen in the middle, the penultimate joint ending in one or two claws, 

 the last joint (often clavate) appearing as an appendage or "thumb" to the iireeeding joint. The 

 legs are seven jointed. The tarsi terminate in two small claws. The legs arc clothed in the same 

 manner as the body. There are two eyes upon each side of the cephalothora.x, quite frequently 

 borne on a distinct pedicel. The genital aperture is situate between the hind cosse. The anal 

 opening is smaller than the genital and placed a little behind it. 

 LCir. 77] 



Fig. 2. — Leptus americanus at left; Leptus irritants at right. 

 Highly magnified, dots under anal extremity indicating nat- 

 ural size (after Riley). 



