Vol. XXVI, pp. 185-190 August 8, 1913 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



' i 1 1 i i ■* 



REMARKABLE LIFE-HISTORY OF A NEW FAMILY 

 (MICROMALTHIDjE) OF BEETLES. 



BY HERBERT S. BARBER, 

 Bureau of Entomology, Washington, I>. C. 



During an attempt, still progressing, to secure by breeding 

 all of the stages in the paedogenetic beetle, Micromalthus debilis 

 Lit., certain astonishing facts have become evident which 

 make the life-history of this beetle the most remarkable in the 

 Cbleoptera, if not one of the most remarkable in the whole 

 • •lass Insecta. Although still far from complete the publication 

 of the life-history, as now known or foreseen, may cause students 

 investigating other life-histories to look for hitherto unsuspected 

 features in their problems, which if not really looked for, would 

 pass unnoticed. 



In a preliminary paper (Proc. Ent. Soc. Wash. 1913, vol. 

 XV, pp. 31-38, plates II and III) the writer has illustrated 

 the paedogenetic mother and young of this beetle, but the sub- 

 sequent observations show that only a small part of the life- 

 history was known at that time. 



Micromalthus presents perhaps the most plastic larval forms 

 yet known, combined with a practically fixed adult form of 

 wide distribution. No close relatives are known, and it seems 

 remarkable that specimens from Michigan, Kentucky and 

 Virginia should exhibit no tendency towards local variation in 

 a species apparently of such feeble powers of migration. It 

 combines in its life cycle — eggs by two methods of reproduction , 

 seven or eight forms of larvae, adults through two distinct lines 

 of larvae, oviparous paedogenesis and viviparous paedogenesis. 

 The species appears to present a beautiful case of sex-determina- 



4S— Proc. Biol. Soc. Wash., Vol. XXVI, 1913. 



