Butterflies flutter around Brisbane in large numbers

Wondering why you’re seeing so many butterflies at the moment? Entomologist Dr Chris Burwell explains the beautiful phenomenon.

BUTTERFLIES are out in large numbers around Brisbane following ideal breeding conditions and fewer-than-normal predators.

Dr Chris Burwell, Senior Curator of Entomology at Queensland Museum, said there seemed to be more butterflies than normal this year due to a combination of good rainfall, warm temperatures and lots of plant growth.

“Spring and early summer, when insect activity typically increases due to warmer temperatures, were dry,” Dr Burwell said.

A Yellow Albatross (Appias paulina) butterfly (pictured left) with Caper Gull (Cepora perimale) butterflies. Picture: Chris Burwell

“However in late January and February the heavens opened and rainfall across the region was well above average.

“This rainfall resulted in prolific plant growth. Butterfly caterpillars eat plants so there was suddenly ample food for them. In addition, temperatures were still warm which also promotes the insect growth.

“However this year there seems to be more butterflies than usual. I suspect this is probably because the parasites and predators of the eggs, caterpillars and pupae of the butterflies are in lower numbers than normal, so more caterpillars have survived to eventually emerge as adult butterflies.

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“When conditions are good, insects can take advantage and increase in numbers quickly. They often lay lots of eggs, can develop from eggs into adults relatively quickly, and in the tropics and subtropics (like Brisbane) can often go through more than one generation.

“Insect numbers after the drought would have been quite low, but the plant feeders like butterflies responded quickly and increased in numbers.

“However the parasites and predators of the caterpillars take a bit longer to respond and thus the butterfly got the jump on their natural enemies and exploded in numbers.”

The Blue Tiger (Tirumala hamata) butterfly. Picture: Chris Burwell

Dr Burwell said there have been a few species in spectacular numbers.

“In late February and early March there were mass flights of two species in particular, Blue Tigers (Tirumala hamata) and Lemon Migrants (Catopsilia pomona).

“I took a long walk at Gold Creek Reservoir in the western suburbs of Brisbane two weekends past and saw at least 35 different species of butterflies.

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“In general, the caterpillars of most butterfly species feed on a small range of plant species that are usually somewhat related. For example Lemon Migrant caterpillars feed on a number of different species of Cassia and Senna plants.”

Dr Burwell said insect numbers would start to drop off in late autumn “and by winter I’d expect there to be few adult butterflies around”.

“In general most adult butterflies aren’t terribly long-lived, usually a few weeks for most.”

Butterflies around a tree at Woody Point just north of Brisbane. Picture: Michelle Smith

Dr Burwell said there were also plenty of dragonflies and damselflies around at the moment.

“Their immature stages are aquatic, so the recent good rainfall has provided ideal conditions for those species that live in standing waters such as ponds, dams and lakes.

“There have also been large numbers of some moth species, which also have plant-feeding caterpillars.

“In February there was an ‘outbreak’ of caterpillars of one moth in particular, a species of geometrid moth (Antictenia punctunculus – it has no common name), in southeast Queensland (including some Brisbane suburbs) and as far north as Rockhampton and west to Chinchilla.

“These large numbers of caterpillars translated to large numbers of adult moths being attracted to lights in March.”

Dr Burwell said Queensland Museum had received lots of “what caterpillar is this” inquires from the public and Curator of Entomology Dr Christine Lambkin was instrumental in identifying the caterpillars and moths.