With recent temperatures soaring well into the 20s and generally about 15 C on cooler days, bees, butterflies and other insects are taking advantage. Vin Malone contacted me a few weeks back whist the weather had slumped once again into cold and damp to ask about a bumblebee he had found.
The creature was pretty much motionless and just sat on a flower doing nothing but looking rather sorry for itself. Vin tempted it with a few drops of honey which apparently triggered a slight revival! However, Vin wanted to know if it was likely that this bumblebee was to soon be a ‘has-bee- n’. My thought was that it could go either way and the animal had probably emerged during a slightly warmer snap and then been caught cold as it were. Body temperatures and stored energy levels drop and the bees become torpid.
Without pollen and the necessary air-temperature to function, then who knows? Anyway, as I said to Vin, this was probably a newly-emerged Bombus terrestris and yes it was cold and miserable! Hopefully, with the support offered the bee would find somewhere safe to sit out the cold weather and is now out and about and enjoying the warmer spring conditions.
Nevertheless, the hazards are not all gone and through the summer, I invariably get readers writing in about dead or dying bumblebees – and often their hollowed-out carcasses lying on the floor. These are the victims of a rather gruesome death via a small parasitic fly called a ‘Conopid’. During June and July, the adult flies sit on flowers awaiting a bumblebee visitation. As the unsuspecting bee lands, the fly emerges and injects an egg into the body or abdomen of the bee. The larva hatches and eats the live bumblebee from the inside and after about ten days of feasting basically occupies almost the entire inside of the bee.
Feeling rather unwell, the dying bee may attempt to burrow into the ground, and the adult fly emerges the following year having over-wintered as a pupa. Nice! Do let me know if you spot these.
Professor Ian D. Rotherham, of Sheffield Hallam University, researcher, writer and broadcaster on wildlife and environmental issues.