In the first blog since our full (but temporary) closure of Lakenheath Fen, I thought it would be nice to shine a spotlight on some of the highlights of spring that we not only will have at Lakenheath; but also what you can see out and about on your daily ‘exercise’ walks in your local area. I hope these are an interesting read and allow five minutes of escapism for our blog followers- and also something to look out for nearer home!
Today it’s all about one of my favourite insects, which we can only enjoy for a short time in Spring while it is on the wing. Looking like it has an identity crisis and can’t decide whether it is a bee, a hoverfly or a house fly, is the bee-fly. While there are nine species in the UK, one is much more common than the rest, and that is the dark-edged bee fly, so called because of the dark edges to the otherwise clear wings. This species of bee fly can often be seen on sunnier, warmers days (perhaps 13c and upwards) feeding on the nectar of it’s favourite flowers- such as violets and primroses, in any sunny, sheltered spot. Bee-flies fly along with their front legs thrust forwards, forming a point as they align with their proboscis (feeding tube) which projects directly in front of them, giving them a very odd profile in flight! From watching them it seems the purpose of this might be to enable them to land ‘feet first’ on any flower that is in front of them, like a primrose or a violet, and hang on while they feed. If you have grape hyacinths anywhere in your garden, they do seem to have a fondness for these too- so keep an eye out.
Photo credit: A dark-edged bee fly (our commonest bee-fly) by Heidi Jones
When it comes to breeding, the bee fly has a bit of a dark side- it is a parasitoid of bee grubs- that is, a parasite that ends up killing, and not just harming, it’s host. Eggs are ‘flicked’ by females into solitary bee burrows, and they land somewhere near the entrance. Beforehand, she often coats them in dust or sand, presumably for camouflage or to add weight to them to help make the ‘flicking’ more successful. Then, they hatch and crawl further into the burrow where they wait, for the bees’ larva to grow to almost full size, before capturing it, killing it and eating it. You can read a bit more about the life cycle of bee flies and watch one in action on the video on this webpage: https://www.brc.ac.uk/soldierflies-and-allies/bee-flies
While you are out looking for bee flies, it’s worth keeping an eye out too for early bumblebees, most of which will be chunky queens looking for a first nest site among leaf litter in sheltered spots. My list so far this spring consists of buff-tailed, red-tailed and tree bumblebees, but our warden Emma has a lovely video of an early bumblebee queen feeding in her garden (if you want a look; find @emslouise on Twitter). You can tell them all apart from the arrangement of yellow, orange, red, buff and white patches and bands in different patterns on each species. Here’s a good guide for those wanting to begin to learn what they are looking at:
https://www.bumblebeeconservation.org/bumblebee-species-guide/
Later on in the season, worker and male bees of the same species will emerge, hatching from the eggs first laid on days like today by the overwintering queens. These often look just like miniature versions of the queens, but sometimes the patterns differ slightly (see the link above). As with learning to ID any group of wildlife, it’s good to try and familiarise yourself with just one or two at a time, and slowly add over time to what you know. After all, we have a whole summer ahead with the bees…
Photo credit: A tree bumblebee queen warming herself at 07:30 on Tuesday morning, on my garden fence!
While you are getting out and about in the coming weeks, please feel free to share any photos you get of bee-flies, bumblebees or other insects with us here, on Facebook (RSPB Lakenheath Fen) or on Twitter (@RSPB Lakenheath). We would love to see what you’ve found! I hope you are all keeping well and beginning to settle into a routine that suits you while we stay home as much as we can! It has been quite an upheaval for the team at Lakenheath but I think brighter days lie ahead and we are beginning to get used to it. by Heidi Jones
Visitor Experience Officer, RSPB Lakenheath Fen