We had our first firefly of the season in the house last night. They are rare visitors at any time of year and we don’t get any at all through the Dry season; we are just on the brink of the Wet now so it was unexpected as well as magical. They are always magical even for local people, I think, but I grew up in Victoria where they are completely unknown so they are even more magical for me than for people who have grown up in the tropics.
But this is (mainly) a natural history blog so let’s look at the science. They are beetles – technically a family, Lampyridae, in the order Coleoptera. There are about 2000 species worldwide, in temperate and tropical climates, and Australia has 25 species in four genera. Most of them are small (about 6 – 10mm) and dark coloured. Wikipedia says:
Many are in marshes or in wet, wooded areas where their larvae have abundant sources of food.
Fireflies hibernate over winter during the larval stage, some species for several years. Some do this by burrowing underground, while others find places on or under the bark of trees. They emerge in the spring. After several weeks of feeding, they pupate for 1.0 to 2.5 weeks and emerge as adults. The larvae of most species are specialized predators and feed on other larvae, terrestrial snails, and slugs.
… all of which accounts for why we rarely see them around the garden and never see them in the Dry.
I managed to catch one on my kitchen floor at exactly this time of year in 2011 for long enough to take photos:
It flew into a room with no lights on, so it was in a dark enough spot for me to notice it by its flashing. Graeme Cocks (Insects of Townsville) has identified three species around Townsville, all in the same genus, and mine seems to be Luciola nigra.
The timing of this shot was entirely a matter of luck. They are so small that you don’t notice them except in very dim light and they never settle for very long so getting any shot at all is quite difficult. In this case, I had it lined up and was simply taking as many shots as I could before I lost it again.
Wikipedia tells us that, “All fireflies glow as larvae. Bioluminescence serves a different function in lampyrid larvae than it does in adults. It appears to be a warning signal to predators, since many firefly larvae contain chemicals that are distasteful or toxic.
Light in adult beetles was originally thought to be used for similar warning purposes, but now its primary purpose is thought to be used in mate selection.”
Atlas of Living Australia adds: “Males fly just after dusk and emit a series of controlled flashes from the light organs as part of the mating sequence; females also flash but have not been observed to fly with the males. Synchronised flashing, well known in some New Guinea species, has been observed in North Qld. Adults are not known to feed, but larvae prey on small land snails.”
They are pretty to see along the river bank in the early evening – often ten or more slowly blinking as they move around. The nearest location I know I’m likely to see them is along the bank of Ross River. It must be time for an evening walk or ride along the bike path between Bowen Road and the Nathan Street bridge, looking down into the scrub.
(The second reference is far more technical than the first.)
- Australian museum: Blue Mountains Firefly (but note that it really only talks about one species – don’t be misled by the fact that it mentions “25 species”)
- Lampyridae of Australia (Coleoptera: Lampyridae: Luciolinae: Luciolini). Authors: Ballantyne, L. A.; Lambkin, C. in Journal: Memoirs of the Queensland Museum 2000 Vol. 46 No. 1 pp. 15-93