65] LEPIDOPTEROUS LARVAE — FR ACKER 65 



considerably smaller than the prothorax. The arms of the epicranial 

 suture unite near the vertical triangle to form a stem which separates 

 the front from the triangle. A third character is the lack of crochets, 

 which seems strange in caterpillars of this size. The body is round and 

 fleshy, and wider in the middle than at the ends. 



Pronuba yuccasella possesses thoracic legs and swellings represent- 

 ing abdominal prolegs, the latter present on segments 3, 4, 5, and 6. 

 These proleg swellings are not found on those Gelechiidae, Coleophori- 

 dae, and Cochlidiidae which are similar enough to cause confusion. 



Frodoxus quinquepunctella is without legs or leglike swellings of 

 any kind, but the closed front is sufficient to distinguish it from such 

 other legless larvae as have the body similarly shaped. An undescribed 

 species from agave in Arizona was also examined and was found to be 

 very similar. 



Family Incurvariidae 



The larvae of this family are, in some respects, nearly as generalized 

 as any members of the order. While it is perhaps an open question as 

 to whether the common progenitor of Aculeata possessed a front which 

 was closed above by the union of the arms of the epicranial suture or open 

 to the vertical triangle, the conditions in other insects and in the Microp- 

 terygidae incline one to the former view. This would place Adela 

 and Incurvaria closer to the common ancestor of all Frenatae than the 

 Nepticulidae. 



Head as high as broad, not retractile; front reaching about two- 

 thirds of the distance to the vertical triangle; adfrontals extending to 

 vertical triangle. Body cylindrical, intersegmental incisions shallow or 

 indistinct; thorax with setae in the usual position but those dorsad of 

 kappa indistinct ; abdomen with kappa and eta adjacent, close to and 

 caudad of ventral edge of spiracle ; mu and Pi group as usual ; thoracic 

 legs present; prolegs indicated only by the crochets which are in trans- 

 verse bands on segments 3, 4, 5, and 6. 



Adela viridella and A. degeerella of Europe have the short and rudi- 

 mentary crochets arranged in two transverse multiserial bands (Fig. 94). 

 Forbes considers this condition to represent the beginning of crochets 

 in Lepidoptera, but it is much more probable that such an arrangement 

 is merely a reduced form of the multiserial circle found in Hepialus 

 larvae. An unidentified American species from Vermont was also ex- 

 amined and in it the crochets were similar. 



Incurvaria koerneriella has but one uniserial row of very rudiment- 

 ary crochets to represent each proleg. This is undoubtedly a degenerate 

 condition. 



