154 



THE EARLY STAGES OF TABANID^ 



observable was shown to be between the periods of the first and the 

 second molts. 



The following table is given by Mitzmain to show the normal growth 

 of a larva. The measurements and the critical stages of life are 

 indicated. 



TABLE I. 

 Progress of Development of a Larva. 



In all biological accounts of the Tabanidae there appears to be one 

 phenomenon which is uniformly noted. This is the remarkable dif- 

 ference in growth shown by individual flies of the same species. The 

 only process in the development which seems to be synchronous is 

 the hatching of the eggs. After that the variations in time of develop- 

 ment are extreme. In Tahanus striatus, for example, some larvae 

 twelve days old measured 3 mm., while others under precisely the 

 same conditions measured fully 11 mm. In another instance two 

 flies emerged as well developed imagos October 31, while twenty- 

 seven of the same brood still remained apparently healthy in the 

 larval stage December 20. 



Mitzmain is the first to mention molting or ecdysis in tabanids, 

 stating that he has been unable to find, "in the very meager litera- 

 ture available," any reference to the molting process in Tabanidae. 

 It is referred to indirectly by King at Khartoum, who found in 



