88 NEW YORK STATE MUSEUM 



The investigations of these scientists cov^ered approximately a dec- 

 ade, 1862 to 1872, which was followed by a long period of ap- 

 parent lack of interest in these larvae, very little original being 

 published from the latter date until the exhaustive studies in 1908 

 by Kahle, who employed modern laboratory methods, demonstrated 

 the general correctness of the earlier observations and satisfied him- 

 self that the process was a true parthenogenesis. It does not seem 

 to have occurred to any one that these larvae might be of great 

 service to the teacher of biology. 



This method of reproduction has been observed by Meinert in 

 Miastor, Oligarces and Meinertomyia (Pero Alein.) and by Kiefifer 

 in Leptosyna. The latter believes the same to be true of Frirenia^ 

 though he has not observed mother larvae, since the females con- 

 tain the unusually large eggs characteristic of genera reproducing 

 in this manner. 



Pedogenesis or close approach thereto is known to occur in the 

 Chironomidae. Grimm in 1870 describes a larval Chironomus in 

 which eggs develop, they escaping, however, from paired submedian 

 ventral orifices in the eighth abdominal segment of the pupa. This 

 must be construed as at least a modification of the process exhib- 

 ited by Miastor and its allies. Professor Johannsen recorded in 1910 

 a pedogenetic larva, Tan y tarsus dissimilis Jhns., which 

 had come under his observation and that of the late Dr James 

 Fletcher, though no data has been published to show the exact 

 character of this process. Professor Johannsen also refers to an 

 account of pedogenesis in this genus observed in Bohemia by Pro- 

 fessor Zavrel. 



Habits. These larvae appear to thrive only in the moist, 

 partly rotten inner bark and punky sapwood which has not been 

 invaded to any considerable extent by other Dipterous larvae or 

 Coleopterous borers. They exhibit a manifest tendency to occur in 

 segregated masses, frequently between loose flakes of bark or in 

 rather broad crevices. These colonies contain in autumn old empty 

 skins of mother larvae ; a number of yellowish mother larvae with 

 approximately five to fifteen young within ; very numerous, small, 

 yellowish larvae showing no trace of embryos ; a number of white, 

 various sized active larvae, frequently white, sometimes semitrans- 

 parent ; and a few quiescent white larvae containing young embryos. 

 Such larval colonies are most likely to be found in somewhat flaky 

 inner bark, especially where conditions allow several larvae to lie 

 side by side (pi. 26, fig. i). 



