692 MEDICAL ENTOMOLOGY 







The larva is of the usual type, and after moulting is transformed into the 

 typical arthropod nymph, which may now either become an adult or pass 

 through another stage which is spoken of as the hypopus. The typical 

 hypopus has no mouth parts and no distinct mouth orifice ; its legs are 

 short and not adapted for walking. It attaches itself, by means of a disc 

 on the ventral surface near the apex of the body, to a flying or otherwise 

 active insect, and is then transported to another locality. Arriving there 

 it leaves its temporary host and carrier, and moults, the next instar being 

 a typical nymph, which after feeding is transformed into an adult. 

 Banks says that the causes which induce a nymph to become transformed 

 into a hypopus are not known. 



Glycyphagus domesticus, Gerv. Dorsal integument more or less granu- 

 lar ; claws weak, almost invisible. Hairs of the body plainly feathered ; 

 anal and genital openings very large, the latter occupying the entire 

 area between the coxae. This species lives in cereals and sometimes 

 causes a transient cutaneous eruption in grocers. 



Rhizoglyphus parasiticiis, Dalgetty. Dorsal integument not granular ; 

 tarsi with stout spines. Leg I never thickened. This species causes 

 the 'water itch' of Indian coolies in the tea plantations of Assam; it is 

 at times a serious pest. 



Tyroglyphus longior, variety castellani, Hirst. Dorsal integument not 

 granular. Leg I of male not thickened. Palpi stout and appressed to 

 rostrum. Suture between cephalothorax and abdomen very distinct. 

 The variety differs from the type longior in minute details such as the 

 absence of short hairs on the ventral surface of the body. It causes 

 ' copra itch ' in Ceylon. T. longior is common in Gorgonzola cheese. 



SUBFAMILY SARCOPTINAE 



The itch mites have long been known to entomologists. They burrow 

 into the skin of man and many of the lower animals, including a few- 

 birds, and cause the diseased condition known as scabies (in man) and 

 mange or acariasis (in animals). * The mites are extremely small and of a 

 white colour and globular shape ; the integument is finely striated and 

 is provided with a few bristles, which are often short and pointed. The 

 legs are arranged in two groups, the anterior pair being usually 

 larger than the others ; they are surrounded with transverse and oblique 

 rings. The tarsi usually end in a pair of stout claws, and there is often 

 a sucker on a long pedicel ; on one or more of the legs the sucker may be 

 wanting, and is then replaced by a long hair. The capitulum is prominent, 

 and the three-jointed palpi are pressed closely to the sides. The mandibles 



