ACARINA OR MITES. 109 



must contain sulphur in some form, as that is the most powerful 

 acaricide. Liver of sulphur is found to be the best form. 



The genus Bryohia, which belongs to the Trombididse or 

 Harvest Mites, has a species destructive to fruit-trees. Its 

 small, round, bright-red eggs may often be seen covering the 

 bark of plum and apple during the winter months. Several 

 others occur in a similar way attacking fruit and flowers. In 

 this family is also placed the Harvest Bug (Leptus autumnalis), 

 fig. 43. This larval mite is said to be the young stage of 

 Tromhidium holosericeum (fig. 41). T. holosericeum is a scarlet 

 mite with a squarish body covered with hairs and papillse, 

 about the twelfth of an inch in length. This mite, which is 

 found crawling about upon the ground, deposits eggs in July. 

 These ova hatch into minute, • six-legged, orange-coloured larvae, 

 the so-called Harvest Bug, which lives as a parasite on the skin 

 of man and many animals, and produces violent itching. When 

 full grown the Harvest Bug is only ^mm. long. 



Family Gamasidae. — In this family the mandibles are pro- 

 vided with very small nippers. They are found on the ground 

 and as partial parasites. The legs are seven-jointed, the second 

 pair being often larger than the rest. 

 There are two claws to the tarsi. The 

 colour is generally light brown, or 

 white ; some are reddish, owing to the 

 blood drawn from their host. The 

 most important form is the Eed Hen 

 Mite (Dermanyssus avium), which in- 

 fests fowls and almost aU birds (fig. 44) 

 This mite, described by Eedi, may be ^^^^^-^U -d"S 

 found in all unclean hen-roosts and (greatly enlarged), 

 pigeon-houses. It is provided with a 



sharp piercing mouth. It is a small mite, flattened, with 

 bristly abdomen and stoutish hairy legs. In colour this gamasid 

 varies from pale yellow to dark red. The larvse, which hatch 

 rapidly from the eggs, are white and six-legged. Like many 



