OF WASHINGTON, VOLUME XVII, 1915 179 



In commenting on this paper Mr. Heinrich stated that in 

 addition to the interesting morphological questions involved, 

 the maxillulae promised to be of prime taxonomic importance as 

 indicating generic differences in the larvae of the specialized micro 

 groups at least. From the material examined it would seem that 

 there are two distinctive types of maxillulse, a simplified type com- 

 mon to the Macros and pyraloid groups and a specialized type 

 common to the Micros, as defined by Mr. Busck. It is also in- 

 teresting to note that while these organs vary according to the 

 manner of feeding, as could be expected, the two types are 

 maintained under the same biological conditions. 



NOTES ON THE HABITS AND ANATOMY OF HORISTONOTUS 



UHLERII HORN. 



(Coleoptera; Elateridoe.) 

 BY J. A. HYSLOP, Bureau of Entomology. 



The larvae of the tribe Cardiophorini in the Elateridse have 

 long been recognized. Schiodte, Ferris and Henriksen. have 

 all given good descriptions and several good figures have been 

 produced of the larvae of the genus Cardiophorus. Notable 

 among these figures is the excellent one of Cardiophorus asset /i.-- 

 by Schiodte. 1 So far as I am aware, the figure of Horistonotitx 

 uhlerii by Mr. W. R. Walton, in the recent Department Bulle- 

 tin 2 on wireworms is the first figure of any other genus in this 

 tribe. At the time this figure was prepared only preserved ma- 

 terial was at hand. This spring through the kindness of Mr. E. H. 

 Gibson, I have received several living larvae of this insect from 

 Charleston, Missouri. 



The larva of Horistonotus uhlerii, as has already been recorded, 

 lives in sandy situations where it feeds on living vegetable mat- 

 ter. The rapidity with which the temperature and humidity of 

 its habitat follows the atmospheric changes is extreme when 

 compared with more impervious soils. The sand rapidly dries 

 out to a considerable depth in dry weather and becomes cold 

 correspondingly abruptly with a fall in atmospheric temperature, 

 the lag being considerably reduced by the open nature of the 

 soil. Elaterid larvae, as we have had very forcibly demonstrated 

 in our rearing experiments with these insects, are extremely 



1 Meta. Eleuth. Obs., 1871. 



2 Bull. 156, U.S.Dept.Agric., 1915, fig. 3. 



