95] LEPIDOPTEROUS LARVAE — FR ACKER 95 



prolegs of this shape, altho a few lower micros with primary setae show 

 similar structures. All of the latter, however, have a trisetose Kappa 

 group on the prothorax while that of the Pterophoridae is bisetose as 

 in other Pyralidoidea. The species examined were Pterophorus elUottii, 

 Oxyptilus periscelidactylus, Platyptilia cosmodactyla of America, and 

 Pterophorus microdactylus and Platyptilia rhododactylus of Europe. 

 In all of these verrucae are developed, except in Pterophorus micro- 

 dactylus where the setae are as in Pyralididae. 



SUPERFAMILY ZYGAENOIDEA 



We begin the discussion of this superfamily with forms which have 

 reached the point of the appearance of well developed verrucae and 

 mesoserial crochets. The verrucae later become more strongly modified 

 and the crochets peculiarly specialized. Another step and the crochets 

 are wholly lost, while the armature includes forms of scoli found in no 

 other larvae. The end of the process is seen in such a slug caterpillar 

 as Prolimacodes, with the head minute and completely retracted, and 

 the body smooth and almost spherical, bearing no processes of any kind 

 except three pairs of minute thoracic legs. 



No larvae of the families Chalcosidae and Dalceridae have been 

 seen. 



Family Pyromorphidae 



Pyromorphid larvae form one of the earliest steps in the evolution 

 of a typical Micro into a slug caterpillar. The Pterophoridae include the 

 most plausible connecting links to the generalized types. The following 

 characters show the close relation to Megalopygidae : 



Head small, retractile, caudal half slightly chitinized; labrum with 

 a small emargination ; ocelli all similar in size, the fifth not set as far 

 caudad of the fourth as in most caterpillars ; primary setae only. Body 

 cylindrical, with large flat verrucae. Prothorax with numerous setae 

 on cervical shield, verruca of the Kappa group large ; mesothorax and 

 metathorax each with the verrucae of the Kappa group and of the Pi 

 group forming single verrucae and with three verrucae dorsad of them 

 on each side. Abdomen (Fig. 59) with verruca alpha fused with beta, 

 and rho and the verruca of the Kappa group well developed ; mu pres- 

 ent; Pi group consisting of one or two verrucae. Prolegs present on 

 segments 3, 4, 5, 6, and 10, each with crochets in a uniordinal mesoseries. 



Triprocris is a western genus ranging from Mexico to Colorado 

 and including eight species. T. smithsonianus, the one examined, has a 

 large subventral eversible gland or fleshy protuberance on the prothorax 

 associated with Pi, and two verrucae, the smaller cephalad of the larger, 

 present between the proleg and the verruca of the Kappa group on 



