NO. 4 FEEDING MECHANISM OF LEPIDOPTERA SCHMITT II 



posterior tentorial proboscis extensor. However, Berlese apparently 

 did not examine the insertions of these muscles and makes no refer- 

 ence to their functions. In discussing the possible mode of extension 

 of the proboscis Berlese followed the suggestion of Burgess, that it is 

 unrolled by its own elasticity. 



The proboscis musculature of one. species of sphinx moth, Hemaris 

 thysbe, may be taken as generally typical of the family. In this moth 

 (fig. ID D) the tentorial muscles are equally well developed and are 

 well spaced on the anterior arms of the tentorium. The cranial probos- 

 cis extensor is moderately developed and in general the whole ar- 

 rangement is well balanced. 



Yet, in some sphingids, there are decidedly inferior proboscis ex- 

 tension mechanisms. For example, the sucking pump in Smerinthus 

 geminatus is so large that there is very little space left for the probos- 

 cis musculature, and the brain also is reduced in size and displaced 

 posteriorly (fig. loC). In this moth there is no cranial proboscis 

 extensor, and only one tentorial muscle, which appears to be the 

 posterior tentorial proboscis extensor judging by its insertion. An- 

 other sphingid, Darapsa pholus (fig. 6B), has an extremely large 

 cranial proboscis extensor. 



Geometridae: The feeding mechanisms of members of this family 

 are weak or degenerate. The proboscis musculature of Haematopis 

 grataria is shown in fig. 9 C. All three stipital muscles are present, but 

 very weak, especially the tentorial muscles. The cranial proboscis 

 extensor is also very short. In the little green geometrids (sub- 

 family Hemitheinae) the proboscis musculature resembles that of 

 Haematopis. 



The geometrid Ennomos subsignarius is typical of further degen- 

 eracy in this family. Only the tentorial muscles are present and they 

 are very weak (fig. 5 B). Each anterior arm is very thin-walled and 

 is considerably enlarged. This enlargement, of course, " lightens " 

 the head by replacing blood volume with air and is of interest in view 

 of the remarkable flights of this insect. Caherodes confusaria re- 

 sembles Ennomos in this respect but has a functional cranial probos- 

 cis extensor. 



The adults of the spring cankerworm, Paleacrita vernata, differ, as is 

 well known, in that the males are winged and the females wingless. 

 However, there is practically no difference between the sexes in the 

 proboscis and its musculature. The proboscis itself, in both cases, is 

 represented by two small lobes. Only a pair of tentorial proboscis ex- 

 tensors can be found, and they are very weak. 



