Back in June we received an email that stuck with me. A person had a question about CO2 attraction in fireflies. Their question pertained to an insect trap that emits CO2 to attract and capture insects. They were concerned about the trap attracting fireflies. The trap claims that it’s safe for honeybees and butterflies because they aren’t attracted to it. At Ask an Entomologist we cannot give pest control advice because we aren’t licensed pest control operators; however, we are entomologists that have a broad knowledge base on insect science. CO2 attraction in insects is complex. What I mean by this is that insects use many stimuli to find their nest, a potential mate, or food. What signals insects use to find food or whatever highly depends on their biology.

So, let’s answer question, “[…] are Fireflies attracted to CO2?”

Kind of. Not exactly. Well, it’s complicated.

Insects can detect CO2, but their behaviors in response to CO2 varies. This will depend on their ecological role and what their environment is like. Social insects such as bees, ants, and termites experience high concentrations of CO2 inside of their nests. The desert ant, Cataglyphis fortis been shown to use CO2 to help them return back to their nest after foraging. Mosquitoes, on the other hand, use exhaled CO2 (in addition to skin odor, etc.) to locate their human host. Bed bugs are also attracted to CO2 – they can detect elevated CO2 levels in human respiration. Many other blood-sucking insects are also attracted to CO2. However, CO2 by itself isn’t enough as an attractant. These insects use other stimuli as well. Many biting insects also use visual cues, thermal gradients, and other odors in addition to CO2. If these insects only picked up on CO2, they would constantly be overwhelmed since CO2 is a universal respiratory waste product. 

Fireflies, which are beetles (Coleoptera: Lampyridae), use bioluminescence to attract a mate or prey. There are many species of fireflies. Most of them eat other small insects, worms, and snails as larvae (beetles go through complete metamorphosis like butterflies do). Adult fireflies will sometimes feed on nectar. Because of their biology, fireflies are attracted to certain environments that have suitable conditions. CO2 isn’t on the top of the list.

At the end of the day, insects use multiple senses to find food. Even mosquitoes use factors other than CO2 to find their host. Beetles have been shown to have the ability to detect CO2, but their induced behaviors will depend on their niche and location.

References

Buehlmann, C., Hansson, B. S., & Knaden, M. (2012). Path integration controls nest-plume following in desert ants. Current Biology, 22(7), 645-649.

Jones, W. (2013). Olfactory carbon dioxide detection by insects and other animals. Molecules and cells, 35(2), 87-92.

Lewis, S. (2016). Silent sparks: the wondrous world of fireflies. Princeton University Press.

Robertson, H. M., & Kent, L. B. (2009). Evolution of the gene lineage encoding the carbon dioxide receptor in insects. Journal of Insect Science, 9(1).

Tauxe, G. M., MacWilliam, D., Boyle, S. M., Guda, T., & Ray, A. (2013). Targeting a dual detector of skin and CO2 to modify mosquito host seeking. Cell, 155(6), 1365–1379. https://doi.org/10.1016/j.cell.2013.11.013

Wang, C., Gibb, T., Bennett, G. W., & McKnight, S. (2009). Bed bug (Heteroptera: Cimicidae) attraction to pitfall traps baited with carbon dioxide, heat, and chemical lure. Journal of economic entomology, 102(4), 1580–1585. https://doi.org/10.1603/029.102.0423