186 K SOUTH INDIAN INSECTS, ETC CHAP. XX. 



animal owing to the irritation caused. "Coolie itch." a disease 

 commonly found in the feet of Indian coolies, is caused by 

 Rhizosdyphus parasiticus, whilst Demodex folliculorum, a peculiar 

 elongate eight-legged mite, is found commonly in the sebaceous 

 glands of the human face ; this latter species, however, is of doubtful 

 importance as a pathogenic agent. Pediculoides ventricosus occurs 

 as a rule in cereals in India but sometimes (e.g.. when infested straw 

 is used to stuff mattresses, etc.) it attacks man and causes severe 

 urticaria ; much the same may be saitl of Tyroglyphus longior var. 

 castellanii, which normally occurs in large numbers in copra and 

 produces " copra itch " by invasion of the skin of those handling 

 substance. 



Acariases usually cause more or less temporary annoyance but 

 an attack of myiasis may produce very severe and even fatal results. 

 The attack of the fly may be more or less casual, eggs being depo- 

 sited on the raw surfaces of wounds or sores, or even taken into the 

 intestine with food, or the fly may normally exist by feeding on 

 living animal tissues during its immature stages. To the former 

 category belon- h as those of the "cheese hopper." the 



larva of a fly (Piophila casei) whose immature stages may be in- 

 gested with food and cause intestinal myiasis, and various " blue- 

 bottle " and other flies which sometimes cause external myiasis in 

 man by infesting ulcers and especially syphilitic erosions of the 

 nose. Rhinal myiasis, or the invasion of the nasal cavities, etc., by 

 the larvae of muscid flies, is indeed probably the most common 

 form of myiasis affecting man in India. Many of the brilliantly- 

 coloured green " blue-bottle " flies (Pycnosoma, Lucilia, etc.) seen 

 commonly on excrement are attracted by any purulent disch 

 from the mucous membrane of the nasal cavity and readily depo- 

 sit egg> (or even living larvae) on such membrane whilst the subject 

 is asleep in the daytime when the flies are active. Sarcophaga rufi- 

 collis has also been recorded as causing human myiasis in India. 

 The larvae bore into the soft parts and even into the bone and may 

 cause very grave injurj or death. Such flie> may. anil commonly 

 do. deposit eggs or larvae in neglected sores or wounds in cattle- 

 Such wounds should therefore always be kept dressed with tai or 

 »e to repel the flies. There are. however, some flies which 

 belong to the second category noted above and of these the common- 

 est in Southern India is probably CEstrus ovis, whose larva lives in 

 the frontal sinus of the sheep, and these animals may often be seen 

 huddled together or holding their noses in the dust in an endeavour 

 to avoid the attack of a fl> which is trying to oviposit in their 



trils. The .finger or Chigoe ( Dermatophilus penetrans), a flea 

 which usualh affects the feet in man. burrowing into the skin 



