Elm leaf curl and woolly Elm leaf curl and woolly apple aphid elmleafcurlwooll203patc Year: 1912 240 MAIXE ACRrCULTriL\L EXPERIMKXT STATION. 1912. rosette (Fig. 462, when a group of terminal leaves are affected) which they cause, producing the next generation, which are also wingless. In the summer great numbers of winged mdividuals are de- veloped. From the fact that Riley recorded 7 consecutive genera- tions on elm and the occurence of what seems to be the elm bark feeding generations of the same species ('known as rileyi) during the on tender elm bark, it would seem either that the
Elm leaf curl and woolly Elm leaf curl and woolly apple aphid elmleafcurlwooll203patc Year: 1912 240 MAIXE ACRrCULTriL\L EXPERIMKXT STATION. 1912. rosette (Fig. 462, when a group of terminal leaves are affected) which they cause, producing the next generation, which are also wingless. In the summer great numbers of winged mdividuals are de- veloped. From the fact that Riley recorded 7 consecutive genera- tions on elm and the occurence of what seems to be the elm bark feeding generations of the same species ('known as rileyi) during the on tender elm bark, it would seem either that the migration from the elm leaves of these summer migrants Fig. 442. Elm leaf curl, in which the alate spring migrants develop before taking flight to apple bark. is partly to apple bark and partly to elm bark or that elm bark colonies as well as leaf curl may be established by the first or second apterous generations. Such a life cycle is indicated, in the accompanying table. This does not account for the genera- tions resulting from the overwintering forms on the apple roots as their sequence yet remains to be studied. The fall migration of the woolly aphid from apple and the mountain ash I have observed but I have not yet from observation linked it with the true sexes on elm. That inference, however, from the evidence of the spring migration to apple is unmistakable. There are still several important details to be worked out for the woolly aphid of the apple and elm. ^^'hether the elm bark
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