a few questions about himalayan balsam

[PMM123]

Can anyone tell me if any native insects/caterpillars feed on Himalayan Balsam?

I was under the impression that nothing did but in my local woodland (which is gradually been overrun by this plant) I've noticed a few leaves with what look like bite marks. Anyone know what could be doing this?

Also do any mammals/birds feed on the leaves?

I've always wondered if any native can outgrow it? Can Nettles?

[Hedera]

Bees love it for the pollen and nectar. It is very invasive and nothing will overcome it as the seeds fly for yards and every one seems to grow. I have not seen anything eating the leaves, looks as if something tried and didn't like them!

[poschiavanus]

A variety of invertebrates do feed on Himalayan Balsam. Certainly a few slugs and snails, and the common froghopper Philaenus spumarius. There is a small fly which feeds in the leaves (a leaf-miner) Phytoliriomyza melampyga. Other insects have been recorded, but I don't have access to the details. None has a serious impact on the plant: there have been research efforts to find suitable bio-control agents.

I doubt if it out competes Nettles because the rhizomes of Nettles can go very deep and sustain the plant for years. The seeds tend to germinate simultaneously and even in the cotyledon stage can form a carpet. The seed-leaves (cotyledons) are big, leathery and are held horizontally. When the plant dies in autumn the dead stalks can also form a barrier to other plants seeding themselves.

Normal management is to pull it before flowering. This, although labour intensive, can be quite effective. It does require 2-3 years effort to deplete any residual seed-bank. I've seen sheep apparently devouring it with great relish, and it certainly suffers if trampled.