In Occitanie, we noticed trees which we were able to identify as Terebinth – or thought we could. The problem is that none of our tree books show the type of growth we saw on these particular trees. They were erect, going reddish in colour, three-four inches in length… and looked a little like sweet potatoes standing on end! Have we possibly made a mistake in identification? Mary Brown
You perfectly describe the galls caused by the aphid Buchnera aphidicola ( Baizonga pistaciae), which lays eggs on the Terebinth ( Pistacia terebinthus) and similar trees. These gall growths – in which the aphid grubs spend summer before emerging and going underground for the winter – can actually reach about six inches long.
What moth In the plant world there are several gall-forming insects affects (perhaps the vines? the most common ones being those that form the circular galls on an oak tree; sometimes referred to as ‘oak apples’) and they seem not to be harmed by acting as host, and instead adapt their growth pattern to the needs of the insect. This includes producing tissue (the gall) that encloses the grubs. Once inside, the grubs feed on layers of cells produced within the gall before eventually turning into adults.
Galls on the Terebinth tree are formed by aphids