44 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



Grass! Foa (1908) also found intermediate sexuparae in Ph. 



Danesii. 



Among other aphids, Ntisslin observed the normal occurrence 

 of intermediate sexuparse in Mindarus. Mordwilko described inter- 

 mediates in Tetraneura ccerulescens with antennae of six segments 

 and compound eyes of 6-10 facets in one form, and well devel- 

 oped compound eyes in another, neither having any trace of 

 wings. In Dryobius roborsis he describes a viviparous female 

 with rudimentary wings and the dorso-ventral (alary) muscles 

 and the longitudinal muscles of the thorax rudimentary or de- 

 generated. He did not observe the offspring of this form. 



Bonier (1908) found these forms in various species of the 

 Chermesidoe. He failed to observe the offspring, but apparently 

 considers the adults as virginoparse. 



In so far as observations on the offspring were noted these 

 records may be divided into groups. It will be noted that all 

 of these observations have been made in species with very speci- 

 alized life cycles, and that this form occurred in the gener- 

 ation in which sexuparse also occurred. All the forms observed 

 in Chermesidse by Bonier, and with one exception, all those 

 observed in Ph. vastatrix by Grassi and Foa, were virginoparse, 

 that is, forms producing a large number of eggs which give rise 

 to parthenogenetic aphids. These virginoparse are normally all 

 apterous at this time of year. The remaining records state that 

 the adults were sexuparse. The majority of the sexuparse in 

 the species under observation are alate, but apterous forms 

 have been described in most, if not all of them. These condi- 

 tions have given rise to various theories, which attempt to explain 



them. 



Balbiani appears to have been the first to discover apterous 

 sexuparaa (in Paraphyl'oxera glabra). He believed that these 

 insects were alates in which sexual maturity preceded full somatic 

 development, in other words, that while sexually mature, the 

 insects were still in the larval form. Dreyfus believed that his 

 observations of intermediates confirmed this theory. Borner con- 

 sidered that the apterous and intermediate sexuparse of these 

 two writers had the same value as his intermediates (which were 

 viginoparse) . He believed, however, that they were merely inter- 

 mediates between the normal virginoparse and sexuparse and 

 were fully mature individuals. Mordwilko interpreted his inter- 

 mediates in Tetraneura ccerulescens in like manner. 



Later (1909) Borner stated that, contrary to the theories of 

 Balbiani and Dreyfus, intermediates are not larvae, since they 

 pass through four moults and attain, with the exception of wings, 

 the more important alate characters. However, he makes a funda- 

 mental distinction between the intermediate virginoparse of the 



