Aphididae of Formosa.— 3. 5 



first instar, though rounded in the latia- instars. Astvijoptcrij.r stijracicohi Takah., 

 as well as A. sfi/racophila Karsch, is provided with some short setae on the front of 

 liead, which occur likewise in the wingless adults, but not in the winged adults. 



The frontal or antennal tubercles are absent in the young nymphs, gradually 

 developing, however, with the moults and are distinct in the fully-grown nymphs, in 

 the genera 3Iacrosipliuin and Amphorophora. In the genera Phorodon and AkJcaia, 

 however, they are distinct, all the instars being provided on the inner side with a 

 tubercle which is smaller than that of the adult; in the genus J/;/2M.s they are very 

 short, but distinctly gibbous on the inner side, even in the first instar. 



The eyes are smaller than those of the adults and are usually less protuberant 

 in the younger instars, but in Eulaclmus they are distinctly protruding even in the 

 first instar. They are composed of three facets in the genera Oreyvia, Ccndaphis, 

 Astegupteryx, Neophi/Uaphi.s. Cervaphis and allies, excepting in the fully-grown 

 nymphs of the winged form where they are composed of numei-ous facets as in the 

 winged adults. In the first instar, the ocular tubercles are usually not visible, but 

 in many species three facets on the posterior portion of the eye are larger tiian the 

 remaining fecets. However, in EliopaloHiphum nymphaeae L., as well as in Shiv- 

 apliis celti Das, they are visible even in the first instar. These ocular tubercles 

 gradually become more distinct with growth. The facets on the ocular tubercles 

 are always tliree in number, and no aphid has yet been found, in which the eyes are 

 composed of fewer than tlirec facets. In my opinion, the three facets of the degene- 

 rated eyes of the apterous forms and most nymphal instars of Oregma, Cerataphis, 

 Astvgopteryx, Cervaphis. NcophyJIaphis and otliers correspond to the facets on the 

 ocular tubecles of many species. The ocelli are always lacking during nymphal life. 



The rostrum is longer in proportion to the length of body in the young 

 nymphs tluiu in the grown ones or adults, especially so in the Lachnina, sometimes 

 reaching beyond the end of the abdomen, as in tJic first instar of Pterochlorns. The 

 sexes of Pe7nphigus and others, as well as the males of iS/o'inaphis, are provided 

 with a rudimentary rostrum in the nymphal stages, but this is not used for feeding, 

 as in tlie adults. 



The antennae are shorter, stouter and less imbricated than in the adults. In 

 the winged forms of Adeijopteryx, in tlie first instar they are rather sleuder, imbri- 

 cated and capable of active movement, in the later instars, becoming (|uite stout, not 

 imbricated and scarcely movable, being appressed to the side of the head. The 

 antennae are sometimes as many jointed throughout all the nymphal instars as in 



