What's up with all the miggies in Port Elizabeth?
Sluggish river flow and proliferation of water and sewage leaks the catalysts, experts say
The outbreak of miggies in Port Elizabeth is probably related to the low rainfall – and could also be connected to the myriad water and sewage leaks around the metro.
That is the view of two experts, who responded on Thursday to questions about the swarms of little bugs that have been the talk of the town for the past fortnight.
Professor Martin Villet, head of the SA Forensic Entomology Research Laboratory at Rhodes University in Makhanda, said the insects were probably from the large family of “non-biting midges”.
“I would need to see a photograph to identify exactly which member of the family it is, but there are about 100 species.
“They like slow-moving water and the low rainfall in Nelson Mandela Bay in the last little while and the consequent buildup of decaying riverine vegetation would have been just right for them to thrive.
“The midge larvae also feed on exposed sewage.”
Predators would soon return things to normal, however, he said.
“The birds will be enjoying a feast and consequently this will likely be a wonderful breeding year for them.
“The message is – just leave them alone.
“The adults don’t feed and live only for a week, so even if they emerge in stages they should be gone in a month.
“Trying to combat them with poison will only harm the environment.”
Wildline and Urban Raptor founder Arnold Slabbert said his view was the miggies were flourishing because of the metro’s water and sewage management problems.
“Everywhere you go in Nelson Mandela Bay there are leaks and standing puddles of water or sewage ideal for these little guys to proliferate.”
Low rainfall had definitely impacted on the metro’s river systems, creating the perfect circumstances for the miggies to breed, he said.
“But illegal extractions are also reducing the flow speed in the Baakens.”
The miggie swarms were also a sign of an environment out of kilter, he said.
“In a balanced system, dragonflies, frogs, fish, birds and bats would prey on them, but we’ve knocked back these predators with pollution, poisons and habitat destruction.
“Around the world, different ‘pest’ species are taking the gap and rising up.”
Meanwhile, UK physicist Andy Reynolds has made some interesting findings on the matter of midge swarms.
According to an article in science magazine Cosmos, calculations by Reynolds published in the Journal of the Royal Society showed that midges routinely experienced stronger acceleration-related forces than those endured by human test pilots.
Reynolds found that midges in flight changed direction so rapidly that they encountered a G-force of 10 – the maximum permitted during a sharp turn by an airforce stunt plane.
While all humans except highly trained and expertly secured pilots would lose consciousness at such levels of acceleration-induced pressure, the insects suffered no ill-effects at all, he noted.
Picking up on findings by US researcher Akira Okuba, Reynolds said midges moved randomly in both direction and acceleration. Nevertheless, the swarm remained intact.
“It maintains cohesion but does not possess global order.
“The midges are bound together by gravitational-like forces and behave like clusters of stars,” he said.