Bee-fly Watch: results so far

Latest update at 3 May 2020: here are the latest reports from #BeeFlyWatch 2020, covering the two spring bee-flies, Dark-edged Bee-fly (Bombylius major) and Dotted Bee-fly (Bombylius discolor), and with the first records now in for one of the two summer bee-flies: Western Bee-fly (Bombylius canescens) - extraordinarily early records for that species.

So far this year we have had 3,199 records of Bombylius major, 211 of Bombylius discolor and two of Bombylius canescens, from over 1,000 people - thank you! We have again broken the record for the numbers of bee-flies reported in a single year.

That doesn't prove that bee-flies are doing better every year of course, as the higher number of records is at least partly a result of more people taking part. And the unusual circumstances of the coronavirus lockdown will also have had an impact, with more people spending time in their gardens, if they are fotunate enough to have them. The overall trend for Bombylius major seems to be that 2020 started a bit later than the very early 2019, and has peaked later, but there has been a more consistent build to a single peak rather than the double-peaks we've seen in recent years. No doubt the sustained run of sunny weather in April will have influenced this.

Bombylius discolor has continued to expand its range, with the first ever sightings in Bedfordshire during 2020, and also an astonishing confirmed record from Hathersage in north Derbyshire, about 100km further north than it has ever been seen before. But the number of records has not gone up in line with the commoner B. major, so it has perhaps not had quite such a good year.

As I write this, the first two record of Bombylius canescens for 2020 are already in, with extraordinarily early April dates - it doesn't usually fly until mid-May. The very rare Bombylius minor is not usually seen before July.

Here's the spread of records across the country up to 5 April (watch on YouTube to see at full size):

Here are the flight periods for the last three years for the two spring-flying bee-fly species (click on the image for larger size):

Chart of records per week for the two spring bee-flies

And for the two summer-flying bee-flies:

Chart of records per week for the summer bee-flies

 

Vice-county league table at 3 May 2020 - just for fun! Note that Western Bee-fly has only just started emerging in 2020, and the table below shows figures for 2019 to give recorders something to aim for!:

County league tables - records per vice-county

 


 

Bee-fly Watch started in 2016, and has been successful in greatly increasing the number of records of these insects. Before the project started the recording scheme was rarely receiving more than 150 records of Dark-edged Bee-fly per year, but this has rapidly risen to an amazing total of well over 2,000 records in 2019 and over 3,000 in 2020 – a big thank you to everyone who has taken part:

Chart of records per year for the four Bombylius bee-flies

With the increased number of records we can start to see some fascinating changes in the flight periods from year to year. In 2016 the flight period for the Dark-edged Bee-fly was quite extended, with a low peak in mid-April. In 2017 warm weather early on meant that the flight period started very early, peaked in early April and ended earlier as well. In 2018 it was a later start again, with a very sharp peak in mid-April and a scattering of records into late June. In 2019 our first two records were the earliest ever, on 17 February (in Sussex and Surrey), and this led to a very early, and very high, peak in March. The same early peak was echoed in the Dotted Bee-fly, although with fewer records.

The end of the flight period is harder to define. We often get reports into July and August but usually without photos and they cannot be confirmed. If you see a bee-fly after mid-June please do try to get a photo, as we know that some reports from late in the season have turned out to be Humming-bird Hawk-moths or other misidentifications.

Flight periods in different years

The Dark-edged Bee-fly has always been widely distributed in Britain, with the Dotted Bee-fly more restricted to the south-west, but there is evidence of a spread for Dotted Bee-fly in recent years. In 2019 there were new vice-county records for Staffordshire (from Thomas Woodhall and Lukas Large) and amazingly in Leicestershire (Alexandra Wallace-Hicks). In Surrey Ryan Mitchell had the first fully confirmed record for the county since 1964 (following a probable but unconfirmed sighting in 2015). Dotted Bee-fly continues to expand, with new records for Bedfordshire in 2020.

The maps below (from the recording scheme atlas) show all records up to the end of 2017. More recent records can be seen via the NBN Atlas pages for Bombylius major and Bombylius discolor.

Distribution maps for Dark-edged and Dotted bee-flies