U8 



Schistocerm americana. E. trigommi is generally distributed throughout 

 the basin of the Missouri and in Oregon, and has also been found in 

 Germany and Holland. The common locust mite in the United States 

 is of the same species as the European one, hence Thromhidium locust- 

 arum, Walsh, is a sjmonym of Euthromhidium trigonum, Herm., of 

 the old world. 



Thromhidium muscarwn, Riley (house-fly mite) is confined to a 

 single host, Musca dom,estica, and has never been induced to attach 

 itself to man. It is generally distributed throughout the United 

 States, in some seasons scarcely a house-fly being found that is not 

 infested with a number of these larvae. Adults of this species have 

 been successfully reared. 



Dunn (L. H.). Studies on the Screw-worm Fly, Chrysomyia 

 macellaria, F., in Panama. — Jl. Parasitology, Urbana, III, iv, 

 no. 3, March 1918, pp. 111-121. [Received 14th May 1918.] 



Chrysomyia macellaria, F. (screw-worm fly), which occurs in great 

 abundance throughout the Canal Zone and the Republic of Panama, 

 is of considerable economic importance owing to its dangerous habit 

 of ovipositing in living, as well as on dead, tissues of man and animals. 

 The number of eggs laid in one batch by each individual fly varies 

 considerably, but under favourable conditions averages 190. When 

 ovipositing in inanimate animal substances, the females exhibit a 

 tendency to lay their egg-masses all together in a heap. The time 

 required for the eggs to hatch varies from 11 hours to 23, the average 

 being about 14 hours. Surrounding conditions of temperature and 

 moisture being so nearly constant in Panama exert but slight influence 

 on the incubation period, though it may be shortened by the body 

 heat when eggs are laid in living tissues. 



The growth of the larvae is very rapid, maturity being reached 

 on the fifth or sixth day. The pupal period is about 4 or 5 days, 

 though it may be as little as 3, or as much as 10. The adults, both 

 sexes of which emerge in about equal proportions, exist on fluids 

 or semi-fluids in material that can be reduced to a semi-liquid food, 

 such as that found in garbage cans, refuse heaps and in decaying 

 plant and animal substances in the woods and jungle away from 

 habitations. 



The females oviposit by preference in the late afternoon or evening, 

 but it is not known whether they remain active after nightfall in 

 search of places for oviposition. Most flies become inactive at night- 

 fall, but this species has been known to deposit eggs during the night 

 in captivity, and gravid females oviposit much more readily in breeding 

 jars when these are covered with a dark cloth. The females are 

 very active, always searching either for food or for a place to deposit 

 their eggs, and are quickly attracted to any animal, probably by its 

 odour, or perhaps by its motion. 



Throughout the Isthmus of Panama this fly by means of its larvae 

 causes more damage and suffering to cattle, horses and other animals 

 than any other Dipterous pest, and if the disease-bearing mosquitos 

 be excepted, the same thing applies to man. 



Eggs are deposited on man in the nasal and aural cavities and in 

 other natural openings of the body, as well as in every exposed wound, 



