1894.] Entomology. 193 
perhaps, on your back under bushes, on your knees in the wheat-field, 
on your stomach in the pasture, with your face down close to a cow 
dropping, and with the summer sun beating down upon your unprotected 
head, watching and watching until the eyes grow dim; but in this way 
only are the unsolved problems in the life histories of injurious insects 
most satisfactorily worked out. 
Biology of the Apple Aphis.—The common Aphis of the apple ` 
(A. mali) has for many years puzzled entomologists by its summer his- 
tory. During June, usually, winged viviparous females leave the 
apple and disappear. In September other similar forms return to ap- 
ple and give birth to the oviparous females which deposit the eggs on 
the twigs. In a paper on the insect foes of American cereals read at 
the recent meeting of the Association of Economic Entomologists, Mr. 
F. M. Webster of the Ohio Experiment Station gave a clue to the 
summer history in the following paragraph : 
“It would appear almost. visionary to advocate spraying apple 
orchards in midwinter to protect the wheat crop, but nevertheless one 
of the most serious enemies of young fall wheat passes its egg stage on 
the twigs of apple during the winter season. I refer to the Apple 
Leaf-louse (Aphis mali Fabr.), Soon after the young wheat plants 
appear in the fall, the winged viviparous females of this species flock 
to the fields, and on these give birth to their young, which at once 
Apple Aphis; wingless viviparous female. Magnified. 
make their way to the roots, where they continue reproduction, sapping 
the life from the young plants. On very fertile soils this extraction of 
the sap from the roots has no very serious effect, but where the soil is 
‘Not rich, especially if the weather is dry, this constant drain of vitality 
soon begins to tell on the plants. Though they are seldom killed out 
right these infested plants cease to grow, and later take on a sickly 
13 | 
