The Importance of the Right Name
When learning about a pest, begin your journey by finding out it’s scientific name. The bug I’m ruminating on today is the Green Vegetable Bug Nezara Viridula, also called green vegetable beetle, stink bug or shield bug. These other names bring you to an array of bugs, not necessarily Nezara V. With the proper name you can’t go wrong. Searching with the scientific name brings you to the best information.
Beware Their Many Disguises
Green Vegetable Bugs go through many phases, each one quite different from the last. The girls were picking beans for tea and came rushing in to get the camera to photograph the cute bugs they’d found. Newly hatched Nezara they were (and they are cute.) Here’s some excellent photos to acquaint yourself with all the phases (instars).
There is a native green vegetable bug which looks similar, but doesn’t have the three light spots along it’s ‘shoulders’. Don’t worry about him, he wont damage your crops.
Natural Predators
Being stinky and big they wont be ambushed by an Assassin bug or eaten by a bird. Predators and parasitic wasps get a look in at the egg stage (black eggs indicate a parasitic wasp has been at work), but maybe not as often as we’d like, Mrs Stink can be quite the egg protector.
Digital Control
I love this term, as if you can press a button and the problem is solved! Pre-infestation (because getting pests at the first sign is the way forward), GVB’s are easily managed by picking them off – especially in the morning (am sure you can relate to getting going slowly), or on a cold day. While you’re at it check under the leaves for tidy clusters of pale, barrel-shaped eggs and rub them off.
Squash one bug and the smell will alert all, sending them plummeting to the ground en masse. In my heavily mulched and over planted wilderness this guarantees their escape. Should your garden be more manicured, you could use this to your advantage. I’ve heard tell of sheets laid down to catch them when they fall. Or rather than squashing them, toss them into a bucket of soapy water as you go.
Success with Neem
If the population is left to grow (about 100 eggs per season per Mrs), then the damage is big – plant malnutrition, undeveloped fruits and ruined fruits (leaving dry, corky bits – see my poor raspberry!). They pierce then suck – especially loving the fruits.
Anything eating your plants is theoretically impacted by Neem, so I asked Bonny from Naturally Neem, if Neem would work on Green Vegetable Bugs. Yes, she said, but the trick is to spray intensively – 3 times a week. It does work.
Neem is not a contact killer, it only damages the insect after it’s been ingested, which is why it doesn’t impact the beneficial insect population. Though Neem is low level toxic to bees, I always spray early morning or late evening once the bees have toddled off to bed.
Everything does of course impact, even ‘friendly’ things. Our human joy is that we have no idea of the impact of our interventions. Use these tools as you must, but know that less is more and we are stronger by far when we intervene as little as possible.
So now I know! Thanks so much for this info kath.
You’re welcome! So great to have a pest plan instead of a pest panic 🙂
They have ruined our corn crop this year, sigh! In previous years they seem to have left it mostly alone, so I wasn’t as watchful as I could have been.
Calendula seems to be a good trap crop for us (in Blenheim) particularly early in the season. They get covered in the instar phases and can then be pulled and burned or sprayed or just dumped in a wheelie bin.
We have had much less psyllid this year (the heat??) but a bumper crop of Nezara viridula 🙂
Yes, calendula is an excellent catch crop for GVB’s – that’s very helpful for everyone to know.
Nature sure keeps us on our toes – in a flexible, go with what she throws at us kind of way – doesn’t she?
Same here low on psyllid high on Nezara (loving your use of this :)) An entomolgist would be the one to answer our pesty wonderings. We had a hot November followed by a cold December. I presumed that summery setback to be the reason for the psyllids late start – I always think of them as loving the warmth. A life times of learning in the garden!
Am really on the GVB hunt now as I don’t fancy a plague next spring.
May your Nezara hunt be a great success!
best Kath
So I take it chickens won’t do the job? (We had a cat that bit a stinky cockroach once, but after foaming at the mouth she went off the idea.)
I spotted a familiar green form toddling along in the nasturtium thicket the other day, but the idea of diving in there with a bucket of soapy water is a little alarming. Who knows what lurks in them thar deeps?
On the subject of chickens, do you have any recommendations or non-recommendations for buying coops in NZ? We’re looking at 2-3 chickens (our garden’s not huge, and we don’t want them getting crowded) with probably a fixed coop in a good-sized fenced-off part of the garden.
Good thinking but my chooks are not at all interested … whos to say yours wont be! So many options for chicken coops! For me its important that chooks can roost – so much healthier when they can fly up onto a perch and the human can easily get in to clean it out. I like this kind of styles – https://chooks.co.nz/collections/housing/products/customised-batten-hen-house
The enemy of my enemy is my friend…
Over the past few years we (and others out there) have been experiencing an explosion in the number of green shield / vegetable / stink bugs (Nezara viridula). We try and be accommodating to the various other creatures we share the world with, however these things are especially annoying with the damage they do to summer vegetables and fruit. In particular we find they enjoy tomatoes, beans and corn with lesser damage done to capsicums and fruit.
While there are a number of documented predators of this insect the only ones I have actually seen in action are poultry and spiders.
A year or two back I introduced a juvenile bug to a small jumping spider who quickly pounced and commenced feeding. More recently some visiting students noticed a decent sized wolf spider (Lycosidae) lunching on an adult shield bug.
It’s reassuring to witness the local ecosystem operating to maintain balance and equilibrium. As the population or one organism increases so does the opportunities for their predators. Knowing this it is essential that our gardens provide adequate and appropriate habitats for these various helpers. And while our tendency for binary, black and white thinking makes us quick to label species as friends or foe we should take a moment to contemplate that, just like humans, other organisms have multiple roles to play, giving and taking as they participate in the dance of life.
Thanks so much Olmec for taking the time to share your thoughts. Yes, nature has it all in hand. I know I’m bashing abut a bit pretending to take the place of predator but I dont quite have your courage to let the shield bugs go! My own evolution unfolding 🙂
Often times I imagine my garden without me and what would take over and what would die away and the tide of pest that would rise followed hot on the heels by predators – the depth and breadth of natures checks and balances, the rise and fall and cycles of all life – diversity is indeed the key. The more I see, the more humbled I am.