THE AMERICAN ENTOMOLOGIST. 



283 



wliich may represent the l;il.)niin, we find 

 two stout spines faintly notched on the 

 outer edge, which are doulitless the man- 

 dibles, and correspond to the two dark 

 lance-like mandibles of other Dipterous 

 larvaj, for they are retractible and run back 

 into the thoracic joints, and remain after 

 the other trophi are detached. The pair 

 of feelers ujjon the upper lateral pieces, 

 which seem to have no motion, might then 

 represent the antenna.% and the two lower 

 pieces, the ma.villaj with their palpi ; while 

 the labium is shown in a chitinous point 

 visible only when the larva extends and 

 raises the outer parts. .V peculiarity in 

 the movement of the maxilla: or lower 

 pair of horny pieces is worthy of note. 

 They move in alternation with one another 

 in the forward and backward, /. c\ uj) and 

 down, motion. The palpus of these lower 

 [Fig, i.-i(i.| jiieces when viewed from 



above is circular, w-ith two 

 dark marks indicating mi- 

 nute apjiendages. When the 

 larva is fresh and plump it 

 is almost white and shows 

 most plainly the swelling 

 of the thoracic joints and 

 the translucences. 'I'oward 

 the period of pupation it 

 becomes more opa(|ue and 

 more contracted.* 

 The pupa (Fig. 148) averages 8.5""" in 

 length. The color is honey- yellow, but 

 varies with age, the head and thorax assum- 

 ing a dark color with maturity. I'he per- 

 fect fly (Fig. 149) is at once distinguished 

 from the succeeding species by its broader 

 form and long proboscis. The whole 

 body is covered with long yellow or ful- 

 vous hairs. The species varies in the 

 color of the legs and in size, some females 

 being larger than the males. The species 

 was originally described from Sierra Co., 

 Cal., and Mr. Williston informs us that 



I'kiouites Mi:s; 

 pup;! (after Riley 



he has a specimen from Washington 

 Territory. 



rKIOinTES MUS. 



The habits of this insect in the larva 

 state are precisely like those of the pre- 

 ceding, and the larva so greatly resembles 

 that of the Systachus that it is well nigh 

 impossible to separate the two with cer- 

 tainty. The head parts are somewhat 

 broader, shorter and less flattened, the 

 niaxilhe more blunt, the labrum paler, and 

 the mandibles sharper and with a smoother 

 outer edge. The thoracic joints bulge 

 less beneath and the thoracic spiracle is 

 more sunken and less conspicuous. The 

 pupa (Fig. 150) is easily distinguished from 

 that of Systtvc/iiis in the broader and more 

 bulbous liead, and in many structural 

 characters. l^he larger head and eyes, 



[Fig. 1.-.1.[ 



Tr[OIHTES MLIS 



ale (after Riley). 



* So far .as we can ascertain there ha.s hitherto been published 

 no reco.s:nizable figure or description of the Bombyhid larva. 

 Diifoiir, in hi.s article above alluded to, describe.', that of 

 Hoiiihylitis iiiajoy very indiflferently, and gives a dorsal view 

 which shows little or no relation to the larva here described, 

 while his description and figure of the mouth parts fail to in- 

 dicate the different pieces \vi- have observed in our larva;, ^'et 

 in general form and structure the true lioiitl'ylins larva will 

 undoubtedly be found to agree very closely with those here 

 described. 



more slender form and short proboscis 

 readily distinguish the fly from the Sys- 

 ttvclius. The se.xes are also readily sepa- 

 rated by the more pronounced transverse 

 rows of white or tawny hairs on the hind 

 borders of the abdominal joints in the 

 female (Fig. 151:. The genus in some 

 degree connects the Autliracini with the 

 more typical Boiiibyliini. In certain lights 

 the tegument reveals a greenish tinge, and 

 the pubescence of the thorax appears 

 generally of a tawny color. The male 

 sometimes has a white tomentum on the 

 front, and in some specimens there is a 

 stump of a vein extending into the discal 

 cell. As the Tn'odifes is not yet known 

 to occur east of Utah, we conclude that 

 Systcvc/ius is the genus most affecting the 

 locusts in the Mississippi Valley. ] 



