Close eye kept on paper wasps
Biosecurity officer Robin van Zoelen has dealt with his share of wasps, he tells Tim O’Connell.
Robin van Zoelen has climbed up into roof voids in the stinking heat and retreated hastily.
The Tasman District Council biosecurity officer says when he started back in the days of the Waimea County Council, he used to spend three days a week dealing mainly with common wasp nests.
‘‘At home I thought I’d dealt to some on the roof, cleaning out the guttering, but there were still some residual ones there – they come flying out of the roof and you can’t just jump off – you get drilled a wee bit.’’
Wasps are generally active from early spring to late summer and work to reduce the impact was now under way by various environmental, conservation and government organisations.
Van Zoelen said while the council was not actively involved in any monitoring of wasp populations, staff were kept busy servicing requests from the public in regard to paper wasps.
‘‘Some of the calls we’ve had are from builders, then we get the issue of two-storeyed dwellings where they’re flying around and it’s quite hard to get access to treat them.
‘‘Any home that has any crack or crevice they can get into, but obviously a wooden building would provide more nooks and crannies for these critters.’’
Of the most regular varieties to be seen around the Nelson region, the Asian paper wasp is identifiable by its yellow and black colouring, while the Australian paper wasp has a red and brown colouring. A European paper wasp species emerged seven years ago in NZ and was confirmed in the top of the south two summers ago.
According to MPI documents, this latest wasp appeared to be well adapted to urban settings, preferring to nest in enclosed spaces such as wall spaces, and thereby increasing its likelihood of being a public nuisance.
‘‘We’ve had the Asian paper wasp there for quite some time but now we have this common paper wasp which was first detected in Picton by a visiting entomologist who saw that something wasn’t right.’’
Van Zoelen said overseas information suggested the recent arrival had the potential to push out other species to the point it might ‘‘dominate’’ the Asian paper wasp.
‘‘Paper wasps in general take a lot of live insects and the caterpillar of the monarch butterfly, that just gets decimated, but also there’s a lot of native insects that have larval caterpillar stage as well, so now we’ve got another predator in the mix.’’
Further afield, national-level concern about the impact of vespula wasps has led Landcare researchers at Lincoln to undergo a biocontrol programme against vespula wasps.
In September, scientist Bob Brown left for the UK to collect new genetic stock of the parasitic wasp Sphecophaga vesparum from the same geographic range our common wasps come from.
The wasp combs brought back are now housed in the insect containment facility at Lincoln, and a good proportion of cells appeared to be parasitised with Sphecophaga.
Controlled releases are expected to begin in 2018.
‘‘Landcare are going to take these critters and put them directly into wasp nests, so if you can come up with a bit of money to help with that, that would be a bloody good thing to do,’’ Van Zoelen said.
The first Wasp Wipeout campaign saw Vespex bait applied to hundreds of yellow stations in Abel Tasman, Nelson Lakes and Kahurangi national parks during the annual blitz on the invasive pests.
Van Zoelen said it was vital that the momentum from the inaugural campaign continued this season to curb the spread of all wasp species.
‘‘These Wasp Wipeouts are an annual event and generally you will get reinvasion – wasps are able to travel a pretty significant distance.
‘‘Anything introduced has massive impacts on the environment . . . with cost to the economy there’s not so much known about the Asian and other paper wasp species, but we can certainly say that some of our native insects that have a larval stage will be at risk, like the monarch butterfly – the ongoing threat to biodiversity just continues to increase.’’
Baits like Vespex don’t work on the Asian and Australian paper wasps. However, Van Zoelen said some good timing and preparation at home could prevent the paper wasp species from spreading.
‘‘In spring when the queens fly around, if you can get them with fly spray, you’re taking out a potential new nest,’’ he said.
‘‘Generally all the wasps will die out except for the odd one who’ll survive as it’s in a structure, but otherwise the queens emerge from hibernation and they have to start everything from scratch so they’re pretty vulnerable.’’
The queen wasp is much larger than the female workers and the males, called drones. Any live wasp seen during winter is a queen.
‘‘Paper wasps in general take a lot of live insects and the caterpillar of the monarch butterfly, that just gets decimated.’’