299 



the head is fully developed and armed with spinose processes ; the pro- 

 thoracic spiracle is apparently on the second segment; and meta- 

 thoracic spiracles are present. For an idea of the general appearance 

 of the larva, see Figure lo, Plate XLIV. 



The larva of Plecia as figured by de Meijere agrees in all essential 

 details with that of Bibio*. 



The characters of the larva indicate that is is structurally very 

 primitive, and in comparison with the adult it is apparent that in this 

 family larval speciaHzation has not gone forward as fast as has the 

 specialization of the imago, the advancement of the latter being evi- 

 denced by the reduction of the number of antennal joints and wing 

 veins. In the Tipulidae the reverse is true, larval specialization being 

 farther along than that of the imago, and distinctly in advance of 

 that of the larva of Bibionidae. 



The presence of the pseudosegment and the additional pair of 

 spiracles on the last thoracic segment readily separate Bibionidae 

 from Scatopsidae. 



FAMII.Y CHARACTERS 



Larva (PI. XLIV, Fig. lo). — Head complete; mandibles op- 

 posed; antennae pedunculate. Body apparently 13-segmented, and 

 with pointed fleshy processes; pseudopods absent; a pair of spiracles 

 on prothorax( second apparent segment), another on metathorax, and 

 one pair on each of the following seven segments ; anal spiracles very 

 large, sessile, situated near anterior margin of segment. 



Pupa (PI. XLIV, Fig. 11). — Antennae rather short, curved, lying 

 across upper half of eyes ; palpi directed laterad. Thoracic respiratory 

 organs very slightly elevated ; legs short, tarsi of fore pair lying over 

 those of mid pair and not extending to their apices, the apices of mid 

 pair extending to apices of wings, apices of hind pair extending slight- 

 ly beyond apices of wings ; wings extending nearly to apex of second 

 segment of abdomen, overlying and hiding all but apices of hind tarsi. 

 Abdomen without spines or bristles. 



HABITS OF LARVAE 



The larvae, as far as known, are scavengers, feeding in the earth 

 upon decaving roots or other portions of dead plants, and are very oft- 

 en found in large numbers closely congregated under fallen logs and, 

 occasionallv, under horse dung and cow dung. The species are very 



*Ti.i(1. V. Eiit., Vol. .53, pp. .59-6.3; PI. IV, Fig. 1. (1910) 



