FIEST SERIES: PEMPHIGUS ACEEIFOLII RILEY. 9 



in " Fauna Suecica," published in 1746, but which was described in 

 the "Acta " of Upsala in 1730 under the name of Chermes alni L. 

 Later, by mistake or oversight, Dr. M. Geoffroy ^ redescribed this 

 latter insect under the name of Psylla viridis, and as inhabiting the 

 alder, without recognizing in it the Chermes ahvi L., which may be 

 considered typical of the genus Psylla^ and a good illustration of 

 which, though without a name, will be found in " Memoires pour 

 Servir a I'Histoire des Insectes," Volume III (1737), Plate XXVI, 

 figure 1 , by M. de Eeaumur. Another figure of the same psyllid was 

 published by «T. H. Sulzer - under the name of Chermes alni L. 

 Evidently this psyllid, from a distance, bears some resemblance to 

 our American insect P. tessellata^ which inhabits the American 

 alders. 



Kalm was therefore greatly mistaken when he supposed that our 

 insect was the same as the European Chermes alni L., or rather, as 

 it is noAv known, Psylla alni. 



Ratzeburg^ refers to this insect in the following words: 



Anf Erleu [alders], ist die im Puppenzustaude selir souderbare, knrzborstige, 

 griiiie, ziiletzt schwarzaftrige, als Fliege, schou grassgriine 1]'" lange P. alni L., 

 welclie meist in der Blattaclisel ihren Sitz hat, sehr, ausgezeiclinet durch lauge 

 weisse Wolle, welcbe beweglich zii werden scheiut, wenu das Insect beunruliigt 

 wird. 



An English translation of the above would read as follows: 



On tbe alders are found very curious, green, short-spined pupae, the anal 

 end of which in time becomes quite black, which eventually change into the 

 1^ lines long, bright, grass-green Psylla alni L. Tliey are generally stationed in 

 the angles formed by junctions of the petioles of the leaves and the twigs. The 

 most obvious characteristic about them is the very long, white wool, which 

 appears to move whenever the insect is irritated. 



All of the above facts prove that the European Chermes or Psylla 

 alni L. has nothing in common with the American insect. 



FIRST SERIES: PEMPHIGUS ACERIFOLII RILEY. 



Observations on the first or original series of Pemphigus acerifolii 

 Riley, inhabiting the soft, or silver maple, Acer dasycarpum., were 

 commenced by me in 1878 and continued, until the year 1911, whereas 

 observations on the alternating, or second series, of Pemphigus tes- 

 sellata Fitch, inhabiting the alders, were started in 1883, or about 

 five years later than those of the former. 



Pemphigus acerifolii issues during the early or middle part of 

 April, or as soon as the young leaves appear, from winter eggs de- 

 posited the previous fall in cracks or under loose bark on the trunks 



1 Histoire Abr6};^e des Insectes, vol. 1, p. 486, no. 3, 1799. 



2 Pie Kennzeichen der Insekten, PI. XII, 1761. 



3 Die Forst-Insecten, vol. 3, p. 187, 1844. 



