Caterpillar expert weighs in on massive Morningside swarm

WHEN masses of caterpillars were spotted on some trees along Avondale Road last week, it sparked health concerns for residents and staff working in the area.

This week, Berea Mail reached out to a caterpillar expert to find out more about the critters. Suncana Bradley of Caterpillar Rearing Group, a Lepidopterists’ Society of South Africa project, identified the caterpillars on a Morningside tree as Red-dotted Euproctis (Euproctis rufopunctata), which are indigenous to the region. Bradley has been rearing caterpillars for the group for the past five years.

“The Red-dotted Euproctis feed on Combretum molle, which I believe is the tree species they’re on currently. The larvae feed on the leaves of the tree, and they do tend to swarm, which is normal and natural for this species,” she explained.

Bradley said the itching sensation experienced is a result of the caterpillar’s hair.
“As with many other Euproctis species, their defence mechanism is urticating hairs, which can cause an intense itch. For this reason, it is best not to handle them unnecessarily and to avoid walking directly under the tree for a few weeks. Wiping down the affected area with a wet towel and applying antihistamine cream will bring instant relief. It is unlikely for them to cause serious health issues. Best is to proceed with caution and avoid walking under trees where they are currently feeding, as well as close windows facing the canopies in question. Any inconvenience is temporary,” she explained.

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Bradley added, most caterpillars feed on leaves, making spring and summer caterpillar seasons.
“This particular species will complete their larval stage of life three to four weeks from hatching. The moths that will emerge a couple weeks later fly at night and are pollinators, as well as an important food source for a variety of wildlife, from spiders to bats,” she said.

Dangers of using pesticide

Speaking to Berea Mail last week, Cllr Ernest Smith noted that some residents had taken to spraying the trees, and he urged the community to contact the Parks Department before applying pesticides, which could be harmful to others and the environment.

“There is an environmental concern raised by the department that spraying the caterpillars could result in a knock-on effect that leads to poisoning of other animals that eat the caterpillars. One must remember that caterpillars also play a part in the pollination of many different plants, and this process would also be impacted. While I agree that these furry fiends need to be dealt with accordingly, as they ‘sting’ people, this also has to be done in a way that works with us as humans and the environment,” said Smith.

Bradley also cautioned against pesticide use.

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“While I do understand why it is done, I can assure you it is the worst course of action when looking at the bigger picture. Pesticides are rarely insect-specific and will discriminately kill all, including the very things that eat caterpillars. More often than not, this will completely throw things out of balance, as well as kill caterpillars that aren’t a problem,” she said.

Bradley listed a range of wildlife that prey on the caterpillars, including birds, bushbabies, shrews, lizards, spiders, praying mantises and darkling beetles.

“Other major caterpillar predators are wasps and flies. They lay their eggs in caterpillars, which then serve as incubators. The eggs will hatch inside of caterpillars and eat them alive from the inside out. This will ensure a new generation of wasps and flies but is a death sentence for the larvae,” concluded Bradley.

City comments *

Commenting on the caterpillar swarm, eThekwini Municipality spokesperson Msawakhe Mayisela said the City has received complaints from residents.

“We have sent teams on different occasions to investigate. The aforementioned species is a seasonal occurrence that is a part of nature. We have informed residents that these caterpillars will pupate into a moth and eventually fly away. Coming into contact with the caterpillar can irritate the skin slightly. We ask that residents be cautious when in the vicinity. In the meantime, we are exploring ways of addressing the concerns raised by residents without harming the trees or the caterpillars,” said Mayisela.

*This article was updated at 13:30 on October 27 to include City comments.