ENTOMOLOGY

60 SANITARY ENTOMOLOGYamong insects introduces an equally troublesome complication into thestudy of the life histories of the heteroxenous nematodes parasitic inhigher animals, for whi,ch insects may serve as intermediate hosts. About~50 species of nematodes have been recorded as parasites of man anddomestic animals. Many of these require no intermediate hosts, butsome are heteroxenous parasites, and a number of these are known to haveintermediate stages in insects and closely related a'rthropods. In thefollowing discussion, in addition to the nematodes parasitic in man anddomestic animals, certain species parasitic in other animals are also consideredbecause of the part played by insects in their life history. Forconvenience they may be placed in two groups, (1) those in which theeggs or first-stage larvre leave the body of the final host in the feces, and(~) those in which the first-stage larvre occur in the blood or lymph ofthe final host and leave the body through ingestion by bloodsuckinginsects.1. Parasitic Nem.atodes Whose Eggs or Lar'tJa! Leave the Body of theFilnal Host in· the FecesProtoapirura muna (GmeHn, 1790) Seurat, 1915This nematode, parasitic in its adult stage in the stomach of variousspecies of rats and mice, is of special 'nterest historically as being thefirst parasite in whose transmission to its final host.an insect was foundto be concerned. Stein in 185~ recorded the presence of encysted nematodesin the larvre of meal beetles (Tenebrio molitor). Leuckart (1867)and Marchi (1867) fed eggs of Protoapirura muria (Spiroptera obtuaa)to meal beetle larvre and followed the development of the young nematodesup to the encysted stage found by Stein. This development is completedin about six weeks after ingestion of the eggs. The development to theadult stage was also followed in mice fed with the encysted nematodes frommeal worms. Johnston (1913) has recorded encysted nematode larvrewhich appeared to him identical with those of P. muna in the body cavityof a rat flea (Xenopsylla cheop;'s).Spirocerca sanguimoltmta (Rudolphi, 1819) Railliet & Henry, 1911The adults of this nematode live in -tumors of the stomach andesophagus of the dog and the wolf. The eggs ·unhatched pass out of thebody of the dog in the feces. Grassi (1888) found encysted larval n~matodesin cockroaches (Blatta orientalis) which he suspected were thelarvre of S. sanguinwlenta. Dogs fed with these encysted nematodes afterfive days showed the larVal free in the stomach; after ten days the youngworms were further developed and ~ere firmly attached to the mucosa