by Adrienne Dale
Wasps can be a nuisance in the hotter months, and their painful sting can cause a medical emergency for some individuals.
Locating the nest may not be easy in covenanted land that is left undisturbed much of the year to regenerate. The insects will be more noticeable during the day when they are browsing and they will go back to the nest at night. Especially on a sunny day, they will be all over the place, and they will not necessarily be very near their nest. It is said that the workers fly within a radius of 200m of their nest unless needing to go further afield for food. The queens are said to fly for some kilometres to find a suitable nesting place. So, during the day the average wasp will go from plant to plant browsing, maybe all over the bracken or on the clover or working at the top of big trees. They may also chew wood to take back to build the nest, seek water from dripping taps, get sugar from flowers or get protein from meat or fish.
Go looking for nests in the early morning when the sun has just appeared or late in the day when the sun is low. At a distance, what you are seeking is vertical rather than horizontal flight. Go searching with binoculars if need be, when the sun is shining through mist or just touching the tops of vegetation. Face the sun and find a background of unlit vegetation. The wasps’ wings will show up in the sun, bigger than other flying insects.That will give you an idea where they are most numerous. Insect eating birds will feed on them so check carefully where you see fantails or swallows. Look for numbers, especially within a metre or so of the top of vegetation. If you notice there are more than half a dozen wasps in a square metre of air, you will probably be quite near a nest. Tread carefully! Move a metre and see if there are more wasps or fewer. Getting warmer? Try another metre until you notice more. A dark background will show up the wings. Vertical movement, up or down, will indicate the nest. And don’t rush. Sometimes there is a spell of a few minutes where there are no insects evident, then they reappear.
A word about direction and speed: wasps going to work or coming home will have a fast horizontal flight path that is clear of vegetation so they can cover large distances quickly. They will fly between big trees and over plants rather than through them. They will follow the topography of the land – up the hill in a paddock or over the top of a house, and down the other side. If they are browsing their movement is much slower and they will go from plant to plant. Returning to the nest, they need a flight path that is reasonably open when approaching the nest. Near the nest they will drop vertically and fly into it. The nest will be in the ground, often in a clearing of sorts, maybe in the tussock, at the base of a flax bush, in a bank or a rotten stump. They may hang around the opening before entering. Wasps may be seen flying out with a piece of grass chewed off in their mouth from widening the tunnel through the long grass. Or you may see them leaving the nest with a bundle between their legs. These ones are excavating so the nest can expand. When leaving the nest they are likely to zoom upwards very fast. Remember this last also applies to any time you disturb them.
Once you have located the nest you need to work out exactly where the entrance is, because that is where you will put the poison. If you cannot see the mouth of the nest your efforts may be wasted. If the mouth of the nest is not obvious, wait till dusk when there are fewer wasps around but still enough to give you a lead. Take some pieces of long grass and wave them gently around your face to deter any curious fliers. If you stand under some flax or tree branches you should be able to keep out of the flight path and get a better view of where they are coming and going from.
Walk around the nest at a discreet distance until you can see some grass chewed off neatly to make a tunnel through the vegetation. Then take a closer look to see the direction they go once inside the tunnel because this will give you the line to follow when administering the poison. It may not be a straight line in.
Now work out how you can best access the entrance later on. You may need to gently clear some vegetation. If the nest is on a bank it advisable to approach from below rather than above if possible. If there is a fallen branch blocking your access to the mouth of the nest, remove it at night so as not to disturb the insects too much. Be aware that there may be more than one entrance, especially if the nest is a big one, and even at night there may be some guards ready to fly out and challenge you.
Return to the nest just on dark, when you can still just see where to go. Cover up well including your head and hands. A beekeeper’s suit is ideal if you have one. Don’t wear a headlight because they will follow the light and may sting you. Use a torch if need be, using a red light rather than a bright white light. Strap it to your wrist and use it sparingly so the guards do not get a fix on the beam. You will need to work calmly, quickly and without disturbing vegetation too much. Very early in the morning can be a good time, well before the sun is up. You may find some sleepy wasps around the entrance waiting to get going or very little activity at all. Once they are flying out fast, or more than one every second, you are probably too late for your own comfort.
There are a number of ways to kill off the nest. A capful of carbaryl powder tipped directly in the entrance should do it. You could try a ladle taped to a 2m stick if you don’t want to get too close. Aim to put the dust where the wasps have to walk on it to get in and out, not just somewhere in the tunnel. A rag soaked in petrol or another volatile liquid can be tied on the end of a stick and shoved into the tunnel, ideally right at the mouth. The rag should completely block the hole. If it doesn’t, never mind. Come back the next night and sprinkle some carbaryl where you can see the wasps crawling through the gap. Avoid spraying anything into the mouth of the nest because the spraying action will disturb the insects. It is important to plan your action carefully, be quick and slink away the moment you have delivered the poison. If you stand around waving a petrol soaked bung they may take an interest in you before you do the deed, and if you hang around after the deed they may seek instant revenge.
Next day there may be a few wasps hanging around still. Leave the nest for a day or two and if there are still some insects around, you may have to give it another go. Sometimes you will get a hole in one, difficult ones can be a par five. Only when there have been no wasps noticeable for several days can you be sure the workers have been killed off. Even then, there may be young or queens in various stages of maturity inside. If you want to dig out the nest to marvel at their astonishingly clever construction, leave it for some weeks before you do and then make sure you have some carbaryl or some petrol on hand to knock off any stray queens that crawl out.
Once the frosts arrive the nests seem to die out and you can wander freely around your covenant again.
You can view the Dale covenant on www.pateke-lagoons.co.nz
All photos taken by the Dales.