October, '17] MARCHAND: REARING TABANIDS 469 



AN IMPROVED METHOD OF REARING TABANID LARViE 



By Werner Marchand, 

 Department of Animal Pathology of the Rockefeller Institute for Medical Research, 



Princeton, N.J. 



The Tabanidse are a group of considerable economic importance and 

 it is desirable for the study of their bionomics as well as for experimental 

 purposes to follow more practical methods in rearing them than has 

 been the case up to the present. Only a few larvae at a time have been 

 reared by authors, and these were usually placed in damp earth to 

 provide them with an environment as close to the natural one as 

 possible. In fact, from De Geer (1760) to the more modern investi- 

 gators, notably C. W. Hart (1895), J. S. Hine, who beginning in 1903 

 has studied the life-histories of several American species, Lecaillon in 

 France, who studied T. quatuornotatus, and others, the larvae have 

 always been reared in damp sand. Hart seems still to have used 

 breeding-cages or boxes of some size, while Hine is the first to propose 

 jelly-glasses, as of more convenient size and having other advantages. 

 In such jelly-glasses, the cover of which was perforated with a few 

 holes, Hine succeeded in raising Tabanus lasiophthalmus from the egg 

 to the adult. Of still more recent investigators, H. H. King (1910) 

 and others have followed Hine's method with small modifications 

 according to circumstances. S. A. Neave (1915) used vessels, made by 

 the natives of the African locality where he made his studies, which 

 were filled with damp sand in much the same way. Patton and Cragg, 

 who wished to raise large numbers of Tabanidse in India without giving 

 much time to their feeding, proposed the use of trays of very large 

 dimensions in which, even in the case of highly carnivorous larvae, a 

 certain percentage will reach maturity. 



All these methods have the disadvantage that the larvae are kept in 

 sand and consequently cannot be conveniently observed. Their pres- 

 ence can be ascertained only by washing them out of their sandy 

 habitat which takes considerable time and also disturbs the larvae; 

 small larvae are easily overlooked and lost; larvae in the act of pupa- 

 tion, or shortly afterwards when the pupae are soft, are often damaged, 

 etc. As, most of the time, the larvae are not visible at all, details of 

 feeding habits or molts of the larvae have hardly ever been noticed and 

 the exact time of pupation and consequently the duration of the pupal 

 period could seldom be determined. 



When beginning an investigation of the life-history of these flies, I 

 found that the larvae of a number of species, and probably of most of 

 them, do not need earth or sand for their well-being, but can be kept 

 very conveniently in test tubes laid out with a rolled-up sheet of filter 



