Leafy burbs look like paradise, but eco-havoc leaves city with hard choices to make

The City of Cape Town, which beefed up its invasive species unit’s response teams to tackle invasive wasps last year, will now not respond to calls from residents who need help on their premises.

A concerned resident made several attempts to get hold of the city to assist with a wasp problem in her garden last year — as per the city’s call to do so.

After several failed attempts, she contacted her councillor, who wrote back (in correspondence seen by TimesLIVE Premium) explaining that she shared her frustration but the city no longer did removals on private properties, and the reasons cited to the councillor were the battle being lost and the budget being redirected to the major borer beetle invasion.

The resident, who did not want to be named, said that invasive wasps kill bees — a vital part of the ecosystem — so it was alarming to discover the city had curtailed its efforts.

The city has defended its efforts on the grounds that eradicating the wasp problem is “impossible”, but denied that it’s because of resources being funnelled towards the major borer beetle problem destroying trees in the Mother City.

Deputy mayor and mayoral committee member for spatial planning and environment Eddie Andrews told TimesLIVE Premium: “When it was first discovered, the European paper wasp (Polistes dominula) or German wasp (Vespula germinica) were considered an early detection and rapid response (EDRR) species, and the intention was to act immediately, and as soon as possible, to assist residents if we wanted to contain or eradicate it.”

“However, after a few months it became clear that it would be impossible to contain or eradicate the wasps, and as such, the programme shifted to managing an established alien species and our methods changed accordingly — which means we are now only focusing on removals from city-owned properties.”

When these invasive pests land here with an abundant source of food and a wonderful climate, the populations literally explode and they do tremendous damage.
— Paul Barker, horticulturalist

Andrews did not specify if that “established alien species” is the borer beetle, but this is now the prime problem of an alien species causing havoc in Cape Town.

According to horticulturalist Paul Barker, the very nature of leafy suburbs and avenues therein are the problem, and it has now come to a head.

He said we stand to lose one in three trees in the coming decade if we do not act quickly and start to preemptively remove trees that assist this pest to proliferate.

He said: “Leafy suburbs with a low diversity of species selection are a prime example of the issues that are arising that we’re not ready to address. We have created a wonderful urban forest with so many benefits and everybody understands this. However, what people don’t understand is that there is a major threat from invasive species that can come into areas like this from other countries, and quickly adapt to our climate and environment and discover this urban forest we have so lovingly cared for.”

He added: “We have concentrated such a small selection of trees into our leafy suburbs that any invasive pest can find food and build the populations quickly, just like we are seeing with the box elder (Acer negundo) helping to spread the shot hole borer.”

With no natural enemies in the mix, the normal balance and controls in the country of origin are not there, so there is “nothing to moderate the population”.

“When these invasive pests land here with an abundant source of food and a wonderful climate, the populations literally explode, and they do tremendous damage.”

So where to from here?

Barker says the most urgent message to spread is that people should remove their box elder trees as urgently as possible to reduce the explosion of the borer beetle population.

He said: