Additionally, it is important to maintain tree vigor with adequate water and fertilizer in the spring. There is no known control. Insect Problems Aphids. Of the many species of aphids, two are very common. The yellowish birch aphid, Calaphis betulaecolens , and the waxy birch leaf aphid, Euceraphis deducta , sometimes occur in large numbers.
Winged aphids migrate in swarms when the infestation is severe.
Birches grown as ornamentals can be sprayed with malathion or insecticidal soap, which are among the compounds registered to control aphids in Connecticut. Imidacloprid applied as a systemic to be taken up by the roots will provide at least one season's control. Consult the label for dosage rates and safety precautions. Birch casebearer , Coleophora serratella . Small cases are formed on the underside of the leaves.