posted 11 years ago
I've noticed some scale insects (with their attendant ants) on our apricot trees for the past few summers, so I asked about it here last year. The advice boiled down to this: If it's not causing serious damage to the tree, let it be as part of your ecosystem, and hope it stays within reasonable limits. Scales suck sap and in large numbers can weaken the plant, but don't directly damage the fruit.
A dwarf lime tree is small enough for you to just pore over it closely and nudge the scales off with a twig. I find myself doing that sometimes when I'm wandering among our apricot trees just kind of loving the trees. It wouldn't work on a large farm but for a home garden can help. Our trees are tall enough that now I can't reach the upper branches, but the scales haven't had a population explosion as I feared so I guess it's alright.
I saw online that if you put a tanglefoot (sticky fly-paper type surface) collar around the trunk of the tree, the ants can't walk up to tend to the scales or aphids so those die. I don't know if that is true, since scales and aphids seem to be sucking the sap where they are. Are the ants helping the suckers or only milking them? Of course this also depends on your tree standing free of other paths for the ants.
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.