After a committee meeting I attended yesterday evening the conversation turned to the puzzle of the Chimneysweeper Moths on a local nature reserve. So far this year 200+ Chimneysweeper Moths have been recorded on the reserve, last year the total for the year was over 400. Chimneysweeper Moths have been recorded on the reserve for many years but not in the numbers now being recorded.

The puzzle is that the Chimneysweeper Moth's foodplant is supposedly Pignut, but no Pignut grows on the reserve. It had been thought that the moth must be feeding on Pignut growing off reserve, but the numbers of Chimneysweeper Moths now being recorded would suggest that the amount of Pignut growing in the area must be relatively large. The area around the reserve is intensively farmed arable land (making access to record difficult) of the same soil type as the reserve so there is no reason to suppose that Pignut is any more prevalent off the reserve then on it.

Does anyone know if Pignut is the only foodplant of the Chimneysweeper Moth or if there are records of the moth feeding on other plants?

Are they migratory or resident on the reserve?

They fly on the reserve every year from now until August, along the banks of a stream that runs through the reserve. Their eggs and caterpillars have never seriously been looked for as they supposedly lay their eggs only on Pignut and there is no Pignut on the reserve.

Pignut is usually regarded as a plant of long established meadows, which will be a reason why it is not found on the reserve, the reserve having been developed out of old gravel workings. The area surrounding the reserve is of intensively farmed arable land with no known old meadows.

All I could find is that it usually feeds on pignut. Perhaps in your area it has found something else to feed on. Looks like you should be keeping a close eye on them to see if you can find out.