GUESTS AND PARASITES OF HALICTUS. 13 



Acarina spp. 

 Two species of mites were obtained, one of which {Ihyobia 

 pratensis Garm. ?) occurred in numbers. 



Class MYRIAPODA, DIPLOPODA. 

 Polyxenes fasciculatus Say. 

 Numerous specimens found crawHng about on the sand. 



Class INSECTA. 

 Order Thysanura. 

 The genus Podnra, represented by many specimens, was found 

 associated with the former. 



Order Hemiptera. 

 Aleurodes sp. 

 The larval form of an Aleyrodid was discovered on the ne.st. 

 Probably it is that of A. corni Hald., the commonest form of the 



Atlantic States. 



Order Diptera. 



Family CHiuoNOMiDyE. 



Ceratopogon hoUensis sp. nov. 



Third vein in part confluent with the first, ending much beyond the 

 middle of the wing, wings in large part hairy, not uniform in coloration 

 but not spotted ; eyes well separated ; tarsal claws simple, of an equal 

 length ; legs not spinose beneath ; metatarsus much longer than the second 



tarsal joint. . . 



Female — Head fuscous, proboscis black. Antennas fuscous, the joints 

 uniformly moniliform, slightly longer than broad, the last two joints longer. 

 Eyes widely separated, the "front yellowish. Mesonotum pruinose, sparsely 

 and uniformly covered with short black bristles. Abdomen dark fuscous, 

 lightly gray pruinose, apically hairy. Pleur.e paler fuscous, smooth. Hal- 

 teres dark fuscous, the stems paler. Legs slender, uniformly yellowish, 

 except that the knees, and the tips of the femoral and tarsal joints are very 

 narrowly black ; tibia, provided with several simple long but slender hairs 

 on the outer edge ; no bristles below, tarsi somewhat hairy, claws small, 

 uniform, simple, empodium small. Wings sparsely covered with short 

 bristle-like hair., more or less serially arranged. These become obsolete 

 at the very base, cinerascent with a pale brown tinge becoming stronger 

 alone the basal part of the course of the anterior heavy veins, gradually 

 interrupted in front of the anterior cross-vein, then gradually recommencing 



