596 Pomona College Journal of Entomoloov 



which thorouglily eradicates tiiem." Wni. H. Ashmead, Can. Ent. XIV. p. 88. 

 1882. 



For no little time Siphuiioplwrii cilrifolii Ashm. was considered a distinct 

 species, but with the study of Aphis gonsi/pii Glover it was learned that many of 

 the above dimorphic forms were of this latter species and that after all Ashmead 

 had not described a new species at all, but had redescribed Aphis gossypii Glover. 

 This is what Theodore Pcrgande writes concerning Aphis gussi/pii Glover: 



"In 1880 Mr. Wm.. Ashmead redescribed this species in his iKimphlet on 

 'Orange Insects,' under tlie name of Siphonophora citrifolii, which he found to be 

 infesting his orange trees, without being aware that the same insect infests also 

 cotton and had been described previously. 



"Again in 1882, Mr. Ashmead, in a paper on the 'Aphidid* of Florida' in 

 the Canadian Entomologist (Vol. XIV, j). <)1), in discussing dimorphism among 

 insects, besides re|)roducing his original description, makes the serious mistake of 

 describing on page 92 another species as a dimorphic form of his citrifolii, which, 

 however, according to the characters given in this description, is neither a true 

 Aphis nor a Siphonophora, but appears to belong to the genus Rhopalosiphum. 

 Mixed colonies of closely related and other species of aphides are frequently found 

 infesting the same ])lant at the same time, which, however, does not indicate 

 dimorpliism." Insect Life, Vol. 7, pp. aiO-311, 1895. 



No doubt Mr. Pergande was referring to the description of tlie dimorphic, 

 viviparous, a))terous females as described by Mr. Ashmead and this is without 

 doubt the Siphonophora citrifolii of Ashmead. Although this may not be the insect 

 which he originally described under that name, he, nevertheless, describes it as a 

 dimorphic form and his description of this is adequate to decide that the Macro- 

 siphum found on citrus trees in this state is the same as the Siphonophora citrifolii 

 described by Ashmead. In spite of the fact that this species has been regarded, by 

 many, as a synonym of Aphis gossypii Glover, this so-called dimorphic form is a 

 good and distinct species and I trust that this description and the accompanying 

 drawings shall serve to give it a proper place in the literature of the family 

 Aphididae. 



The species resembles in a number of ways the Rose Aphid {Macrosiphuv) 

 rosae Linn.) and the Pea Aphid (Macrosiphum destructor John.) and might easily 

 be taken for either. Figure 194 shows a comparison of the antenna?, cornicles and 

 styles of these three s(*ecies. It will be seen that the number of sensoria on the third 

 antennal article of the winged female vary greatly, there being more than twice 

 as many on M. rosae than on either of the other two; more on M. destructor than 

 on M. citrifolii. The third antennal article of M. citrifolii and M. destructor have 

 three or four sensoria each, while there are thirteen or fourteen on the third article 

 of M. rosae. The third article of M. rosae is longer than that of M. citrifolii, while 

 that of M. destructor is longer than either. The cornicles of M. rosae and M. 

 citrifolii have a restriction at the tip with a mosaic figure in the restricted area, 

 while the cornicles of M. destructor are not restricted near the tip. Those of M. rosae 

 are dusky througliout, tlisose of M. citrifolii are dusky on the apical half or two- 



