This year, our Bumble Bee Recovery Team in Ontario expanded from one field crew into to three dedicated field crews, allowing us to increase our survey effort in more areas of the province. Our teams were out searching for yellow-banded bumble bee queens for our conservation breeding program from both southern Ontario and northern Ontario. Aisa Psenicnik, one of our newest bumble bee conservation technicians, was stationed in Thunder Bay for six busy weeks in the spring. In total, our teams were able to collect 54 yellow-banded bumble bee queens (up from 31 in 2017!). During her time in the field, Aisa learned how to quickly spot and identify bumble bees – however, this didn’t stop other insects from tricking her into thinking they were bumble bees too! Here’s what Aisa has to say about encountering bumble bee mimics in the field.
This year, I was hired as a bumble bee conservation technician for the Bumble Bee Recovery Program’s spring field season. I was able to learn a lot about where to look for bumble bees, how to identify them, and most importantly, how to catch them! Once you get the hang of it and know what you are looking for, bumble bee queens are relatively easy to spot – they are big and fuzzy with a flight pattern that is fairly distinct compared to other insects. However, there were a few insects that were able to fool me from a distance, and surprisingly, right up-close too! These bumble bee look-alikes, or what are often referred to as bumble bee mimics, are engaged in a phenomenon called Batesian mimicry. Batesian mimicry is a defence mechanism whereby a harmless animal adopts the warning system (such as a colour pattern) of a more dangerous animal. In this way, the mimic gains protection from predators because it is mistaken for something that might pose a threat to them—like the sting of a bumble bee!
On my first day, I learned how to use an extendable net to catch bumble bees off of tall willow trees, and I couldn’t wait until I caught my first bumble bee queen. When I finally caught something in my net, I was excited when I thought it was a bumble bee! However, my first catch in the field turned out to be a bumble bee mimic instead. The insect in my net was a species of syrphid fly (or hover fly); it was fuzzy, with an alternating black and yellow pattern on its body, and I was surprised to see how much it resembled a bumble bee (although comparatively small to a queen).
There are actually quite a few mimic flies to watch out for when surveying for bumble bees in the field. For example, the tri-coloured narcissus bulb fly (Eristalis flavipes) mimics the tri-coloured bumble bee by copying the yellow-black-yellow pattern on the upper part of the body (thorax) and the distinctive orange band on the abdomen. I have caught this fly a few times and didn’t realize what it was until I had transferred it to a vial to take a closer look!
Upon closer inspection, these flies can be distinguished from bumble bees by observing a few key features that are usually easy to see in the field:
The bee-fly (Bombylius major) is another common mimic fly. They look a bit like a cross between a bee and a mosquito. The bee-fly resembles a bumble bee with its fuzzy body, and although smaller than a bumble queen, it is large enough that at a distance it might be mistaken for a bumble bee worker later in the field season. These flies are not completely harmless however; they lay their eggs in insect burrows and their larvae are common parasites of digger bees, solitary wasps, and beetles.
Flies are not the only mimics out there. The clearwing moth (Hemaris diffinis) acts as a sort of double agent. Fuzzy, with pale and dark stripes, it is easy to mistake for a bumble bee from a distance when it is foraging. I have often spent time chasing these moths thinking they are bumble bee queens, only to be left feeling deceived upon finally catching them. Because of its size and quick flight pattern, it is also often confused with a hummingbird at a distance, and is commonly referred to as the hummingbird moth.
During my first field season, I was deceived quite a few times by various bumble bee mimics, and I don’t suppose they will be my last encounters! Although our field work revolves around bumble bees, we also get to witness an incredible diversity of insects that populate the fields, valleys, and roadsides that we have visited, and that’s pretty special!
We hope you enjoyed meeting Aisa, and learned a bit more about some of the bumble bee mimics we encounter in the field! Next time you’re out searching for bumble bees, take a closer look – it might just be a syrphid fly or a clearwing moth!
– The Bumble Bee Recovery Program.