Becca is back for seconds this week, see what she thinks of the much maligned horse fly!
We’ve been experiencing an exceptionally warm, sunny June so far – great for walking on the reserve, enjoying the wild flowers, birds and butterflies. However, those conditions are also ideal for a less welcome resident – the horse fly!
As the RSPB is an all nature conservation organisation, this week I set out to try to convince the rest of the team that horse flies are in fact very interesting insects with (a few) redeeming qualities.
Horse Fly, taken by Jeroen Shel RSPB Images
If you hear a horse fly buzzing around, it’s likely to be a harmless male. They lack the scissor-like mouth parts of the female so won’t bite you. As is often the case in nature, it’s the female of the species that you need to be wary of! Her flight is silent, so often you will only notice her after you’ve been bitten.
Ouch! So why do they bite? Although it can be painful for us, they do have a reason... it is believed that the females need a ‘blood meal’ before they lay their eggs to enable them to develop successfully. As well as humans, most mammals, some reptiles and even amphibians can be the unwitting providers for a horse fly snack.
I must get to those redeeming features...
If you’ve ever seen pictures of a horse fly close up, you’ll notice that they have the most amazing, iridescent eyes. It is possible to identify certain species of horse fly by the stripes and patterns of their eyes. It’s also possible to distinguish between the sexes; the eyes of the male touch in the middle whereas female eyes are separated by a gap in between.
Horse fly, taken by Phil Cutt RSPB Images
Males are important pollinators and some species possess a long proboscis adapted to drink the nectar of specific flowers.
Horse fly, taken by Ernie Janes RSPB Images
Female horse flies are very agile and are able to perform the ‘Immelman Turn’ (an aerial manoeuvre named after a German WWI pilot). This involves a vertical U-turn as shown in the diagram below and enables the fly to reposition and attempt a second attack very quickly.
Diagram credited to R/C Airplane World
However much they are disliked, horse flies still have an important place in the food web here at Coombes Valley, providing small birds such as blue tits and fly catchers with the nourishment they need to raise their chicks successfully.
Healthy numbers of insects means healthy numbers of food prey for predators at the top of the food chain such as the sparrowhawk. This bird of prey was once so badly persecuted that their numbers were in rapid decline. Fortunately today, they are thriving and healthy numbers of top predators is a sign of stable ecosystem.
If we are giving nature a home, then that also includes the unpopular, but fascinating horse fly.