844 



AN INTRODUCTION TO ENTOMOLOGY 



In the genus Melandirta, of which two species have been found 

 on the Pacific Coast, the outer lobe of the labella is mandible-like, 



Mi+Cui 

 Fig. 1094. — Wing of Dolichopus coguilletli. 



and doubtless functions as a mandible. For descriptions of these 

 remarkable flies see Aldrich ('22). 



The males of some species have the fore tarsi exceedingly elon- 

 gated and slender, with the last segment in the shape of a compara- 

 tively large, oval, black disk, as shown in Figure 1093 ; in others the 

 front tarsi are plain but the middle ones are elongated, thickened, and 

 very black ; and in still others the first two segments of the antennae 

 are ornamented with coarse black hair and the arista covered with a 

 black pubescence. In several cases the males have been observed to 

 display these ornaments before the female when courting. Detailed 

 accounts of these observations are given by Professor Aldrich in the 

 monograph of Dolichopus by Van Duzee, Cole, and Aldrich ('21). 



The larvae live in a variety of situations, some in earth or decom- 

 posing vegetable matter, some in the burrows of wood-boring larvae 



Fig. 1095. — Wing of Psilopodius sipho. 



and also under bark; some in the stems of plants; and some are 

 aquatic. But little is known regarding the habits of the larvae; )t i& 

 said that some species feed on decaying vegetation, while others are 

 believed to be predacious. 



