Larva on hogweed

Larva on hogweed

Observation - Larva on hogweed. Description: I've had a large number of these creatures eating hogweed (cow parsnip) leaves this year. But not enough to kill them or stop them flowering. As the hogweed can be very invasive of my grassland, I'd like to know what they are and how to encourage them. Si

I've had a large number of these creatures eating hogweed (cow parsnip) leaves this year. But not enough to kill them or stop them flowering. As the hogweed can be very invasive of my grassland, I'd like to know what they are and how to encourage them. Size 5mm.