Witch-hazel (Hamamelis)


Spiny witch-hazel leaf gall
Ansel Oommen, Bugwood.org
Found in buds, the Spiny witch-hazel leaf gall houses developing aphids inside of it. It starts as a green and fleshy projection that hardens into a brown, spiky object by winter. These aphids can also be found on birch, where they are known as the River birch aphid. Aphids from birch trees migrate to witch-hazel to create the next generation of aphids that will emerge the next spring.

Witch-hazel cone leaf gall
Lacy L. Hyche, Auburn University, Bugwood.org
Similar to the spiny witch-hazel gall aphid, Witch-hazel leaf gall aphids split generations between birch and witch-hazel plants. The gall induced on witch-hazel is cone-shaped, leading to another common name being the Witch-hazel cone gall aphid. Aphids emerge from cones in the late spring/early summer and fly to birch to lay eggs. This next generation, which looks like Whiteflies on birch, matures and sends one final generation back to witch-hazel to produce the overwintering eggs.


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