Summer rainfall and termites
Summer rainfall in the Mallee makes everything come alive. I reckon a big part is the emergence of huge numbers of subterranean termites from their underground chambers. The termites become food for lizards like the Nobbi Dragon (Diporiphora nobbi) and Regal Striped Skink (Ctenotus regius), but also for innumerable birds, especially the White-browed Babblers and Singing Honeyeaters.
Nobbi Dragon (Diporiphora nobbi)
Regal Striped Skink (Ctenotus regius)
A Summer thunderstorm is enough for termites to kick-off a colonising flight. It got me wondering (and worrying) about what I was seeing and was the house at risk from termite attack.
4 January 2021: Winged reproductives emerging from an underground nest after 24 mm of rain.
13 January 2022: a 34 mm thunderstorm and these termites are mating and shedding their wings.
Termites have several castes (forms) within the colony: one main queen (large and long-lived), a king, the workers which gather food, tend young, and maintain the nest, the soldiers which defend the nest, and finally, the reproductives. The reproductives are winged as adults and are able to survive for short periods outside the colony. Termite castes which live within the colony have a thin skin and rely on the humidity within the nest to prevent them from drying out. Reproductives have slightly thinker skin.
Reproductives will either take over from the queen if she dies, or leave the nest on a colonising flight to form new termite colonies. These flights occur during warm, humid weather and after the flight they shed their wings to set up a new colony (1). So, I was seeing multiple colonising flights triggered by the summer thunderstorm.
But will they eat the house? The Australian Museum says there are 258 described and 90 undescribed termite species in Australia, but only a few wood-damaging species are of concern to humans. The most destructive species overall in Australia is Coptotermes acinaciformes (2). New colonies generally require moisture to establish. Ha! Not going to get that in the Mallee (unless there’s some leaking pipes or over-irrigation). Apparently to identify our termites, I need to collect soldier castes, which have distinct head or mandible morphology that allows species identification when viewed under a microscope. Perhaps that’s a job for another day. Whilst we don’t have the awesome mound-building termites of northern Australia, I think these guys look pretty cool and I hope they’re friendly.
Look, to be honest, I don’t know a lot about termites. These might not even be termites, but I loved the way the little towers popped up after the rain.
Generally speaking, termites are the good guys of the Mallee. “Despite their small size, a large number of studies have shown that both ants and termites have substantial beneficial effects on ecosystem properties and processes that would be almost impossible to value.” Termites are the most important detritivores in arid and semi-arid ecosystems and have a role in soil turnover and development, and as producers of macropores which allow the infiltration of water into parched soils (3). They are also hugely important as a food resource for lizards in the sandy, arid areas (4).
But like many invertebrates, they’re poorly known - 90 undescribed species! There’s a job for someone. But I do love that the researchers are burying toilet rolls to monitor termite abundance, and calling them “buried cellulose baits”. One study buried 600 rolls in 2014, specifically unbleached, unscented, 400 sheet, 2-ply toilet paper. Lucky it wasn’t in Covid-19 times (5).
More information:
Check out this cool time-lapse photography from Collect the World (Facebook)
1 https://australian.museum/learn/animals/insects/termites/
2 https://australian.museum/learn/animals/insects/termites-as-pests/
3 Effects of Ants and Termites on Soil and Geomorphological Processes
4 The Diversity and Abundance of Lizards in Arid Australia: A New Hypothesis
5 Testing the assumptions of the pyrodiversity begets biodiversity hypothesis for termites in semi-arid Australia
First published 4 January 2021. Updated 16 January 2022.