. Manual of fruit insects. overing the open-ing leaf-buds and blossoms, and itsometimes injures young wheat inthe fall. The yellowish-green, wingless, vi-viparous stem-mothers hatch from theshiny, black, oval winter eggs as soon asthe apple buds begin to open, and mostof their progeny develop into wingedparthenogenetic, blackish females () which leave the apple in May. Afew may remain on the trees throughtwo or three more generations, oruntil July. In 1893 we found thatthese spring migrants could be readily colonized on June andmeadow grasses (species of Poo), and we succeeded in follow
. Manual of fruit insects. overing the open-ing leaf-buds and blossoms, and itsometimes injures young wheat inthe fall. The yellowish-green, wingless, vi-viparous stem-mothers hatch from theshiny, black, oval winter eggs as soon asthe apple buds begin to open, and mostof their progeny develop into wingedparthenogenetic, blackish females () which leave the apple in May. Afew may remain on the trees throughtwo or three more generations, oruntil July. In 1893 we found thatthese spring migrants could be readily colonized on June andmeadow grasses (species of Poo), and we succeeded in followingthe insect through thirteen parthenogenetic generations on thesegrasses from late in May until November. Then some developedinto the winged return migrants, but others continued to breedand finally lived through the winter on these grasses and onwheat kept under outdoor conditions. Curiously enough, all thegenerations grown on the grasses were alternately wingless andwinged viviparous females. They were much smaller and. Fig. 163. —The apple bud-aphis, a parthenogenetic fe-male with wing pads. 152 FRUIT INSECTS darker colored than those on the apple, and have been describedas a different species, Aphis annum Oestlund. On the grassesthey lived on the blossom heads, but mostly on the stems, andsome of them at the base of plants. It has been suggested thatthe species is biennial, the progeny of the spring migrants fromthe apple living on grasses and grains until the autumn of thesecond year before going back to the apple. Late in September we found many winged viviparous femalesreturning to the apple trees. These return migrants were verysimilar to the spring migrating form, and soon gave birth to ovip-arous females, which were wingless and of a yellowish-green ordark green color. About the time these females matured, or threeor four weeks after the return migrant females came from thegrasses, there came to the trees the more slender, light greenish-brown colored winged males
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbenefic, bookyear1915
