Skip to content

Do bumblebees know when ants are in?

Bombus terrestris queen visiting Digitalis flowers with ants outlined
Bombus terrestris queen visiting Digitalis flowers with ants outlined

I took a few photos of a large Bombus terrestris bumblebee (queen I think) visiting foxglove flowers in St. James Park, London on a fine day last week. When I looked closely at the images I noticed a few ants within individual foxglove flowers.

Bombus terrestris queen visiting Digitalis - ant outlined
Bombus terrestris queen visiting Digitalis – ant outlined

Lasius niger worker ants – and other species presumably – often tend aphids on foxglove flowers (Digitalis purpurea) and may forage for nectar on the flowers (1). But ants are not always welcome visitors to the flowers; they are detrimental to their fitness for a number of reasons (2). Firstly, they are usually too small to be much good as pollinators and secondly, their aggressive behaviour may put off more useful pollinators! They are ‘nectar thieves’ taking nectar without providing any mutual benefit for the plant, and also potentially diminishing the appeal of the flower to hard-working pollinators such as bees, which might stay away. Some plants try to keep ants away by using physical or chemical barriers, or offering them an alternative source of nectar, via extrafloral nectaries – EFNs (3). Foxgloves also have guard hairs to deter smaller bees from entering the flower (4), but it seems that ants can easily pass through these.

Bombus terrestris queen visiting Digitalis - with ant on flower rim
Bombus terrestris queen visiting Digitalis – with ant on flower rim

Does the presence of the ants affect the behaviour of the bees? Bumblebees can apparently detect whether another bee has visited a particular flower recently and thereby avoid wasting time by visiting a depleted nectar source. Do they do the same with ants? Ants do leave scent markings – e.g. pheromone trails marking a source of food – and laboratory experiments have shown that bumblebees potentially could avoid ant-visited flowers (1), if they put their minds too it! But they do not seem to use this ability much in the wild. Perhaps the ants are not taking very much nectar, so it is still worthwhile for the bee to visit the flower. Also, the bumblebees are in and out so quickly, and there are so many individual flowers clustered together on a foxglove inflorescence that it is not worth taking the time to sniff out whether ants had been in or not!

Bombus terrestris queen visiting Digitalis flowers
Bombus terrestris queen visiting Digitalis flowers

Would the bumblebee avoid a flower with an ant sitting in it? Perhaps big bumblebees like this one are not bothered by ants? Or do the ants get out of their way? Anyway, my observation was that the bumblebees were in and out of the flowers so quickly it was very hard to tell whether they avoided flowers containing individual ants. Perhaps they just steam rollered over them! Someone way know the answer to this?

  1. Ballantyne, G., & Willmer, P. (2012). Floral visitors and ant scent marks: noticed but not used?. Ecological Entomology, 37(5), 402-409.
  2. Willmer, P.G., Nuttman, C.V., Raine, N.E., Stone, G.N., Pattrick, J.G., Henson, K. et al. (2009) Floral volatiles controlling ant behaviour. Functional Ecology, 23, 888–900.

rcannon992 View All

I am an entomologist with a background in quarantine pests and invasive invertebrates. I studied zoology at Imperial College (University of London) and did a PhD on the population dynamics of a cereal aphid (Metopolophium dirhodum) in the UK. I spent 5 years with the British Antarctic Survey studing cold hardiness of Antarctic invertebates and 17 years with the Food and Environment Research Agency. My main interests now are natural history, photography, painting and bird watching.

One thought on “Do bumblebees know when ants are in? Leave a comment

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Think Like A Plant

A personal blog of a plant lover

The Five Species Challenge

Biodiversity recording for beginners


a celebration of nature

The Carrs Wetland Project

Farming, Landscape, Heritage and Conservation

jidjottings, by Lowell A. Goldsmith, MD

Musings on skin and the universe


Thailand's amazing insects photographed in the forests around Chiang Mai

Tangled Bank

The natural world, inclusive bushcraft, evidence-based environmentalism

The Quagga

Science Blog of the SciComm Students @ Natural History Museum, Zoological Society of London & University College London

Exploring Colour

New Zealand

Gwen Pearson

Entomologist. Educator. Writer. Nerd.

Davina's observations

Observations of nature and science

Michael Whitehead

Plants, pollination, evolution, ecology, natural history.

The year of the fly

Exploring the families of British Diptera

Jonathan Pomroy

Wildlife & Landscape Artist

the glyptodon

Stories of natural history


Research blog of Renee Rossini

Notes on a Spanish Valley

Award-winning blog - Living in rural Andalucia

The Art of Blogging

For bloggers who aspire to inspire

walter sanford's photoblog

Showcasing some of my digital photography and videography.

%d bloggers like this: