Yorkshire Status: Fairly common and fairly widespread resident.
Formerly Melanchra pisi.
Sutton & Beaumont, 1989: Widely distributed and fairly common throughout all five vice-counties. In the east of the County, at least, this seems to be an insect of fairly open habitats, being fairly common near and on chalk grassland in the Wolds and also being recorded in agricultural areas of North Holderness and the Vale of Pickering (PQW). Larvae are common on sea buckthorn at Spurn, VC61 (SLS pers. comm.).
2012 (CHF): This species is much more common in the uplands but can be found in smaller numbers in many lowland areas. The biggest numbers tend to be from the west of VC64 and from Spurn.
2020 (CHF): We quite rightly get concerned about some of our rarer declining moths, but what about the common ones which are not doing well. Which ones should we be worried about? Which is the House Sparrow of the mothing world. Do we have a mothing equivalent of the Passenger Pigeon - once the most abundant bird in the USA but alas gone forever? Not that I'm suggesting we shoot moths for food, but you get my drift. Do we need to worry about species like these? If we do, one candidate might be Broom Moth.
It will be no surprise that Porritt in 1883 regarded it as "generally common" however he did point out that "Mr Dobree says it does not occur in Holderness". A surprising statement as the larvae at Spurn feed on Sea Buckthorn and it has always been regular there, though less so recently. There will have been few records from Spurn in Porritt's time but I would have expected some records from inland Holderness. There were no alarms when Sutton and Beaumont in 1989 said "widely distributed and generally common", and indeed this seems to have been the case in Yorkshire until about 1993.
Since then, the situation has altered here. Just looking at one year can be misleading. In 2020 we had 141 records of 301 Broom Moths from 55 sites. It's the best year since 2015 and I even one in my garden which isn't a common event. That's a lot of Broom Moths and you could be forgiven for thinking they are doing well. If you look however at the graph, for the last thirty years the numbers have taken a nose dive. OK they have levelled off a bit recently, but they have to, otherwise if they followed the trend line, we would be counting a negative number of moths in a couple of years. Rothamsted data is alarming. The graph shows a steady fall that shows no intention of levelling out. It's not one of those species where there was a big fall in the 80s and 90s and then a levelling out as we see with so many species, instead it's as near to a straight line as you can get with moth data and it's heading downwards. Fast.
The third edition of our Field Guide was printed in 2017. There is no note of alarm at all. The situation is apparently rosy. "Common throughout the British Isles, particularly abundant on northern moorland". Not a sniff of a problem. We now however have our shiny new Atlas and it's woken up a bit. "Its abundance has decreased severely since 1970 and the distribution of this moth has also decreased significantly particularly in central and south-east England". Indeed it has. The map itself might be misleading at the black dots are post-2000 and if you had made them post-2010 it would look at lot different. This moth has deserted large tracts of lowland England.
Some moths react to warming temperatures by moving north. Others move to higher altitude. Broom Moth falls into the latter category. Of all Yorkshire's moths, this is the one whose uphill movement has been the most dramatic. In the 20 years between 1998 and 2017 it moved upwards an average of 6.3 metres per year. That means that the altitude of the average Broom Moth record has changed from 62m to 188m in 20 years. If you didn't catch that the first time, I'll repeat it. 62m to 188m! That's quite a lot. The 2020 red dots show that it still does occur in lowland areas eg Strensall Common, Terry C's garden at Haxby, Thorne Moors, a couple of places in VC61, but for how much longer? It is incidentally one of the few species which occurs on Iceland. Perhaps that is where it will end up.
Finally, a useless fact. It's scientific name, pisi is because Linnaeus wanted to point out its love of garden peas. In Europe apparently it can be a pest in the vegetable patch. I don't think this has been reported in the UK, where the distinctive and attractively-striped larvae are more likely to be found on many other plants such as heather, bracken, brambles and indeed broom.
Finally finally, don't forget when you send in the records, its genus changed from Melanchra to Ceramica. I had to manually alter a lot last year.
Recorded in 165 (83%) of 200 10k Squares. First Recorded in 1883. Last Recorded in 2022. Additional Stats