M YCETOPIIILIDjE . 



387 



a 



Tig. 307. 



bers of an undescribed species (Fig. 307 ; a, larva ; 6, pupa, 

 magnified three times. Fig. 308, head of the larva greatly en- 

 larged ; a, antenna; Z, labruin ; m, mandible; ra#, maxillae? 

 mp, maxillary palpi? </, gena?) which seems to differ from 

 Dufour's figure of the European M. pallipes in the form of the 

 wings and their venation, as well as in the 

 form of the pupa. The larvae were first seen 

 in abundance on the 26th of June. in the 

 crevices of the bark of the elm from which 

 flowed a sour sap mingled with dust, and in 

 this putrescent mass the slender white worms 

 glided swiftly about. The body is long and 

 slender, scarcely tapering towards either end, 

 and consists of twelve segments besides the 

 head. Like the larva of Scenopinus and 

 Thereva, each abdominal ring is subdivided 

 by a well defined false suture ; but the hinder 

 division in this larva is about one-fourth 

 shorter than the rest of the ring. It is .36 

 of an inch long. The head is pale honey yellow, and the body 

 pure white. The three thorac: 3 rings are marked posteriorly 

 with honey yellow, with a pair of large round pale spots low 

 down on the side of each ring. It moves with great activity, 

 keeping its mouth-parts constantly moving, pushing them into 

 the dirt. The pupae were found sticking 

 straight out from the bark, being attached 

 by the spines on the tail. They were 

 straight, long, cylindrical, the thorax 

 being but little larger than the base of 

 the abdomen. The head is square in 

 front, ending in two lateral horns, and 

 the abdomen is covered with stout 

 spines, especially at the tip. It is .20 

 of an inch long, and is pale honey yel- 

 low and covered with dirt. The flies appeared June 27th, and 

 for six weeks after flew about the trees. The head is black, 

 the thorax and abdomen brown, with a leaden hue ; the abdo- 

 men is a little paler, being whitish beneath, but darker towards 

 the tip. The legs are pale, a little darker externally, especially 



mp 



Fig. 308. 



