Botanophila seneciella

A single Ragwort plant grew in my garden in 2024 and was deliberately left. As soon as I read James Emerson's tweet about having found Ragwort flower heads topped with froth caused by this species I went out into the garden to check my Ragwort. There were at least four such frothy flower heads, one of which I brought indoors and dissected to find the puparium (which was wedged into the base of the flower). I attempted to rear this through but failed dismally. I have seen these forthy heads referred to as galls but I'm not quite clear if that is technically correct?

Botanophila seneciella puparium, North Elmham (Norfolk, UK), 30th July 2024

These were not dissected. I discovered that there's a second species in the genus that occurs on Ragwort, Botanophila jacobaeae, but we think this species does not produce the foam. However it's worth noting that none of mine have been successfully reared through to confirm the ID with reference to the adult fly.

Botanophila seneciella signs, North Elmham (Norfolk, UK), 30th July 2024

This fly was on one of the Ragwort flower heads and looks much like the adults of this species, but unfortunately after taking its photo it eluded my attempt to catch it and confirm.

possible (unconfirmed) Botanophila seneciella, North Elmham (Norfolk, UK), 30th July 2024

The next day I found more signs of this species at two other sites.

Botanophila seneciella signs, Wendling Beck Environmnent Project (Norfolk, UK), 31st July 2024