APPENDIX. 317 



In 1897, and again in 1898, 1 made certain that the species that was 

 injuring the apple trees in our state bred on them throughout the season, 

 and that there was no alternate food plant; therefore no true "migrant" or 

 "return migrant." 



Tree No. 33 in the experiment orchard became very lousy in 1898, and in 

 the fall of that year it was observed that eggs were being deposited in large 

 numbers. I decided then to begin a series of observations on the specimens 

 developing on this one. tree. Both sexes were present in numbers November 

 1, and already many eggs had been laid. Copulation was frequently observed, 

 and a number of pairs were preserved for study. Both sexes are wingless, 

 and at no time did I notice any winged males. The females are of a uniforni 

 velvety green, sluggish in motion, and rather more than one-twentieth of 

 an inch in length. The males are smaller, much more active, and a dull 

 yellow-green in color. The eggs are large in proportion to the insects, dark- 

 green in color when laid, becoming black in two or three days. They are 

 regular, rather elongate-oval in sliape, and smooth, shining. Oviposition 

 continued until near the end of November, and at Moorestown I found 

 specimens yet laying eggs in early December. 



To preserve a considerable number of the eggs, tree No. 33 was given 

 comparatively little and irregulai- pruning. After the tree started in the 

 spring of 1899, and aphids began to develop, observations were made at first 

 almost daily, and specimens were preserved at frequent intervals through- 

 out the season. Nearly fifty vials of shoots, with the insects in all stages. 

 in either alcohol or formalin, were accumulated, and from these nearly one 

 hundred and fifty slides, containing upward of one thousand examples, were 

 mounted. All of these were carefully studied in connection with the notes 

 made during the summer, to bring out the complete life-history. Unfortu- 

 nately, it was assumed that all the summer broods were alike, and during 

 that period specimens were not preserved as often as earlier or later in the 

 season. I am not certain, therefore, that there are not more generations 

 than I have given, and there may be even more forms than I discovered. 

 To make certain of my species, I submitted mounted specimens to Dr. L. O. 

 Howard, Entomologist of the United States Department of Agriculture, and 

 he promptly transmitted to me the report of his assistant, Mr. Theo. Per- 

 gande, who knows plant lice at least as well as any other student in America. 

 Mr. Pergande says that the specimens are undoubtedly Aphis mali Koch, 

 and may be the species called so by Pabricius. It is not the species called 

 Aphiii mali by Fitch, Thomas, Weed, and other American authors. There- 

 fore, it must not be assumed that the accounts given by them are erroneous 

 because they do not agree with that given here. They simply apply to 

 another species, and we can no longer speak generally of "the" apple louse. 

 The term "apple-plant louse" is suggested for the species here described, 

 because it has no alternate food plant ; the other form might be called the 

 "apple and wheat louse." 



LIFE-CYCLE. 



The earliest time known to me for the appearance of this insect is March 

 28, when I received from Marlton, Burlington County, apple buds already 

 covered with specimens. The date of the first coming may be generally 



