TROMBIDOIDEA 



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SUPERFAMILY A: TROMBIDOIDEA. 



The Trombidoidea include the following families, which are of 

 importance in medicine: — (i) Trombididse; (2) Tetranychidae ; 

 (3) Cheyletidae. 



Family Trombidid^. 



Trombidoidea with soft skins, and chelate mandibles adapted for 

 biting. 



There are two important genera, which may be differentiated 

 as follows : — ■ 



A. Distal segment of palp with single claw — -TroMhidium. 



B. Distal segment of palp with two claws — MicrotroMhidium. 



Trombidium Latreille, 1795. 



The larvae of this genus are the harvest-mites, and are widely 

 distributed. Leptus americanus Riley and L. irritans Riley are 

 American species, being found in the United States and Mexico. 

 Trombidium tlalsahuate Le- 

 maire, 1867, is the Tlalsahuate 

 of Mexico. The zoological 

 names of the ' pou d'agouti ' 

 of Guiana, the ' niaibi ' of New 

 Granada, the ' Colorado ' of 

 Cuba, the ' mouqui ' of Para, 

 the ' bste rouge ' of Martinique 

 and Honduras, are not known. 

 It must be confessed that there 

 is a great deal of uncertainty 

 about the genus and species of 

 these larvae, and the subject 

 evidently requires revision. 



Morphology. — ^They are six- 

 legged larvae with prominent 

 claws on the tips of their legs, provided with a powerful hypostome, 

 which they drive through the skin. Around this hypostome the 

 tissues of the host are supposed to form a tube. 



Life-History. — ^Onl}^ the larvae appear to be parasitic ; the adults 

 apparently are not. 



Pathogenicity,— They cause itching, redness,, and swelling of the 

 affected part, which, if scratched, may become eczematous, and 

 even at times suppurate. 



Treatment.— Sulphur ointment kills them. 



Genus Microtrombidium Haller, 1882. 



Definition. — -Trombididae in which the distal segment of the palpus 

 terminates with two stout claws. 



Remarks.— These mites are quite common. Thus Microtrom- 

 bidium autumnalis Shaw, 1790, is the harvest bug of England, and 



