Excerpt: Invasive Wasps
A selection from my draft memoir, Spring in the Cottage Garden.
Today I am sharing an excerpt from my current work in progress titled âSpring in the Cottage Gardenâ. Itâs a diary-style memoir that I first drafted early in my gardening journey, and I hope to complete edits and publish soon.
My thoughts on predator control have changed since writing this, so I thought it would be interesting to share this - written at a time when I was just starting to learn about gardensâ role in wildlife conservation.
Next week we will return to our usual Saturday newsletter, with a guest post about predator control for wildlife from my friend and fellow gardener,
.If youâd prefer to listen to this newsletter, hit the play button below:
First drafted October 2021
I have come to terms with almost every animal in our garden. Possums, rats, mice, rabbits, probably ferrets and stoats: the rodents that are so ostracised here in Aotearoa for their impact on native bird populations have even been reluctantly accepted as part of the ecosystem (I considered trapping but theorised that we do more for birds than against them, so the scales are in the birdsâ favour). Iâve accepted root-chomping slaters, plant-felling cutworms, sap-sucking aphids, and even accepted a few vines of bindweed.
Wasps, however, lead me to still consider a career in assassination. Not because they do harm to the plants I am growing (they are, of course, a pollinator) but because of the harm they do to the precious biodiversity in my garden.
We have five ânuisance waspsâ that have been accidentally introduced to Aotearoa during the 20th century: German, common, and paper wasps. They are all carnivorous and, amongst other things, eat caterpillars. While I donât mind so much that they make a dent in the cabbage whiteâs population (which is thriving), it does sadden me to see the kahukowhai, kahukura, and monarch caterpillars, which I look out for and actively encourage, be attacked and eaten.
Wasps arenât their only threat, of course, but I make the exception for them because they truly are an exception: they have no natural predators in Aotearoa. This means their number keep going up, uncontrolled, and they greater the numbers, the more they eat.
Praying mantisâ are eaten by birds, as are slugs and snails; aphids are eaten by ladybugs; rats and mice by cats, and flies are eaten by spiders (I once watched as a ground swift spider, having caught and bound a fly, sucked out its juices and must admit that it was oddly fascinating).
Wasps, however, have free reign. There is a product currently on the market in the form of a protein bait containing the commonly used insecticide fipronil. The wasp eats the bait, and then carries back to its nest for mass extinction. I considered using this but I donât think itâs fair â itâs not just the wasps that are causing the decline of our butterflies. Through pesticide use and habitat destruction, humans are also at fault.
(The wasp situation is due to change, as our government will be introducing two wasp predators that apparently kill only these wasps: a hoverfly (Volucella inanis) and a wasp-nest beetle (Metoecus paradoxus)Â I am generally hesitant of introducing species as pest control, after learning about the cane toad fiasco in Australia, and all the failed attempts we have had here (rabbits come to mind) but our government seems to have had success in the recent past.
In 2014, we chose to introduce a butterfly from Japan to control the invasive Japanese honeysuckle plant. So far it has done no harm! Perhaps there is hope for the butterflies of New Zealand yet.)
Iâd love to hear your thoughts on wasps & other predators,
Zenobia
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carrer in assassination! LOLLL
Thank you for sharing this. Snails have been eating most of my garden and I have a hard time killing them. Maybe the government here in California could help me out!! Till then, going to try to dump them in the compost so the city can take care of them for me đ
Thank you for this. Will be eager for your follow-up on the government introduction of the two wasp predators.