75] LEPIDOPTEROUS LARVAE — FRACKER 75 



tinguish this family from all others. The affinities are clearly with the 

 true Microlepidoptera, not with the Zygaenoidea or Bombycoidea. 



Thyris differs from Dysodia in the shape of the front, which in the 

 former is nearly as broad as high, with adfrontals bounded by straight 

 lines, while in Dysodia it is long and narrow with nearly parallel sides 

 and the adfrontals are widened above. 



Three other genera with unknown larvae are recorded from North 

 America, in addition to Thyridopyralis. The latter does not belong 

 in this family. As the name indicates, the imaginal characters conflict, 

 but those of the larva clearly place T. gattacrandalis, the only species, 

 in Pyralididae, subfamily Phycitinae. The pyralid structures are the 

 bisetose Kappa group of the prothorax. the unisetose Pi group of the 

 other thoracic segments, and the position of alpha on segment 9 where 

 it is farther laterad than beta. 



Family Aegeriidae. 



Sesiidae, the name used in Dyar's List for this family, is the one by 

 which it is best known, but as it has been discarded in all the more 

 recent s.ystematic work, there seems to be no reason for continuing the 

 error. It appears to be clearly established that Sesia belongs in Sphing- 

 idae and that Aegeria is the oldest genus in the family. 



The larvae are well known borers and at least two of them are 

 serious and very common enemies of the peach. All are so uniform 

 that their separation is difficult. A key to the known species has been 

 published by Dyar (Beutenmiiller, 1900). The one given below is based 

 on practically the same species but employs different characters, and it 

 is hoped that later workers will add to the number of good generic 

 distinctions as well as to the number of known larvae. The following 

 characters are common to all the species : 



Head smaller than prothorax. with strong mandibles; front and 

 ocelli various; labrum shallowly concave at tip. Body cylindrical, 

 incisions rather deep. Prothorax with beta farther mesad than alpha 

 and with Kappa group trisetose, mesothorax and metathorax as in 

 Tortricidae (Fig. 40). Abdomen with kappa and eta adjacent and 

 other setae as usual except that they are disarranged on segment 8 by 

 the change in the position of the spiracle ; segment 9 with all setae in a 

 single transverse row (Fig. 57). Spiracles broad and elliptical, much 

 larger and higher on eighth than on other abdominal segments. Prolegs 

 always bearing two transverse bands of uniordinal crochets (Fig. 99). 



Genera of Aegeriidae : 



