138 ENTOMOLOGICAL NEWS. [April, 'iS 



A Second Mycetophila with Dung-bearing Larva 

 (Diptera ; Mycetophilidae). 



By FREDERICK KNAB and R. H. VAN ZWALUWENBUUG, 

 Bureau of Entomology. 



( Plate VIII) 



From the majority of published statements one gains the 

 impression that the larvae of the numerous species of the 

 genus Mycetophila are very much alike in appearance and 

 habits. They are described as elongate white fleshy larvae 

 with a darker chitinous head. They are stated to occur more 

 or less gregariously in fungi, either burrowing in their interior 

 or living between the lamellae. Larvae of this genus living 

 singly and exposed, upon the foliage of higher plants, appear 

 to have been recorded but once.* We are able to make known 

 a second species of such habits, discovered in Porto Rico by 

 the junior author. \Ye initiate the subject with a brief synop- 

 sis of the principal biological data brought out by Doctor 

 Holmgren in the paper just mentioned. 



These highly remarkable larva? were discovered bv the 

 third Nordenskioeld expedition in the rain-forest region of 

 Peru and Bolivia. The larvae occurred singly upon the leaves 

 of bamboo (Chusquea spp. ) and carried upon their backs a 

 black shell ; they so closely simulated in appearance a small 

 gastropod, such as Ancylus, that at first they were mistaken 

 for such. The larva is short and stout and the protecting shell 

 carried upon 'its dorsum is constructed of its own excrement 

 and shows a series of rings or creases indicating the success- 

 ively added layers of material (Plate YIII, fig. 4). That the 

 shell has a protective function is shown by the fact that when 

 the larva is touched at one side it draws the shell in that direc- 

 tion. The larvae occurred but sparingly and crept about slow- 

 ly on the bamboo leaves in search of food. Forward movement 

 was accomplished by successive muscular contractions along 

 the ventral surface in the manner of a gastropod ; but the 



* Holmgren, Nils, Monographische Bearbeitung einer schalentrag- 

 enden Mycetophilidenlarve (Mycetophila ancylifonnans n. sp.V Zeit- 

 schr. f. wissensch, Zool., vol. 88 pp. 1-77, pis. 1-5 (1907). 



