National shortage of monarchs caused by wasps

This topic contains 7 replies, has 5 voices, and was last updated by  caroldee 7 months ago.

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    –National shortage of monarchs caused by wasps, says butterfly farmer–


    If you haven’t seen many monarch butterflies this year, its…because there’s a national shortage this summer.

    Commercial butterfly growers Ian and Jill Knight released about 100 monarchs into the wild on Saturday. The Knights’ farm has four tunnel-houses, each one filled with hundreds of monarchs in various stages of development; when the butterflies are mature, they are either sold or released into the wild.

    Ian said this summer there was a “huge shortage” of monarchs, which he believed was primarily due to the Asian paper wasp.

    “They’re the biggest threat [to monarchs] at every stage of life, from egg and caterpillar to chrysalis and butterfly,” Ian said.

    “Last year we had about 300 butterflies in one tunnel-house ready to release, and the next day I went in, the floor was just littered with dead butterflies and there was one wasp that was in there, in a stinging frenzy.”

    Ian said he killed the wasp, but the damage was mostly already done: of the original 300 butterflies, 150 died.

    Ian Knight collected dozens of monarch butterflies from their protected tunnel-house to release into the wild.

    The Knights run a business, Occasional Monarch, which sells monarchs to be released at special events like weddings, funerals, and unveilings. They send carefully boxed-up butterflies through the post in chilled containers, ready to be released after warming up again.

    The butterflies are completely unharmed by the process, as being kept in cold, dark conditions simply sends them to sleep. The Knights have even kept butterflies in the fridge over winter, feeding them every ten days, to give themselves a head-start for breeding when it warmed up again.

    They said wild butterflies often came to the farm to lay eggs through the protective netting onto the swan plants inside, but this year the number of wild monarchs returning was less than previous years.

    Jill said the couple regularly sweep the tunnel-houses looking for wasp-invaders that managed to sneak their way into the protected area, and kill any paper wasp hives they find.

    “We try to keep our farm clear [of wasp nests], but if there are any on neighbours’ properties they come over here,” she said.

    Unlike common or German wasps, paper wasps only take live prey and so do not respond to poison bait like Vespex. Instead, paper wasp nests must be killed individually with over-the-counter pesticides.

    Paper wasps are different from common or German wasps, and can be identified by the long, dangling back legs that hang below them when they fly. German and common wasps tuck their legs up to fly.

    There are three species of paper wasp established in New Zealand, all of them introduced: the Asian paper wasp, Australian paper wasp, and European paper wasp.

    Jill said she and Ian were in it for the long haul to keep butterflies safe in New Zealand, even if they eventually tired of the commercial side of things.

    “We’ll keep doing this, if there was ever a threat to the monarchs, just to tide them over until something can be done about the paper wasps.”

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    Like many I have been getting very few eggs, I have seen the odd wasp around though so perhaps any that are laid are being taken by them.
    I’ve got to the point where if I happen to be around to see a monarch on a swan plant I go out and check, if she’s laid an egg I’m bringing it (on the leaf) inside – so far only have three but they have all hatched and happily munching away in safety.
    Has been a bit of discussion on my neighbourly site recently about ideas for deterring wasps on swan plants and amongst the usual suggestions of citronella, mint etc one lady has put cedar wood off cuts around the base of the plants, apparently they don’t like the smell and seems to have put them off for now anyway! Worth a try perhaps for those who have access to off cuts, or even douglas fir has a similar smell.



    Once things return to “normal”, i.e. just the usual predators/parasites – and/or the wasps start leaving the caterpillars alone, most people will lose interest in the fact that there may be something happening…

    However, yesterday I spoke with Professor Myron Zalucki in the University of Queensland and he asked me to watch for any female who came into the garden and looked like they were laying but weren’t. He suggested I put her into the butterfly house with a swan plant and nectar flowers and see what had happened. After 24 hours she should be dumping eggs… and we would see if they hatched.

    He also gave me further steps to take if the eggs didn’t hatch or if no eggs were laid.

    But today we have managed to find eight eggs, and I’ve seen more being laid on fleeting visits to the garden… but I’m too busy to follow monarchs around. So not sure where this is going to go!



    Good thoughts, Leslie. This is not an objection (at all) and your thoughts are appreciated, BUT (there had to be a but!) I guess no-one else would have done anything about collecting data. Because I have WWOOFers collecting eggs for me on a daily basis – and there were no eggs to collect six or seven or eight weeks ago and since, it brought this to my attention.

    I guess that’s why I did something about it, creating a survey and getting people interested. It has taken a lot more of my time than I should be spending on it, once again putting the pressure on me. I’m not complaining but of course with something like this, if it happens again next year, we need to be set up BEFORE it happens so we can put the plan into action. This wasn’t planned – it was just a gut reaction.

    I am talking with Professor Myron Zalucki at the Ecology Centre, University of Queensland this afternoon – he has done a lot of work with monarchs in the past. Will see what he thinks, if he thinks it’s something out of the ordinary or just the usual boom and bust of insects depending on their environment.



    Maybe observations could be in the form of snapshots. several over day/s rather than one over weeks to avoid having too many variables. Forest and Bird did a bird survey that had members of the public counting birds in a specific defined area (your own backyard and sky above it)for the period of 1 hour on a day of their choosing within a given timeframe. The rules were clear and simple and it was low overhead for people.



    There are many keen amateur observers that could help but they would need very specific things to record so back to the Project management basics I guess.

    It will be a very wide problem area to try and define. So break it down to smaller manageable pieces to define and be specific what is to be observed for each piece so amateur observers don’t confound the issue. The usual subjects of interest will help .. e.g. predators, plants .. I’m thinking maybe weather variations. Having better information on how far our Monarchs travel would be useful. I wonder if there may be some localized small gene pools leading to greater expression of fatal genes?

    My lot are not helping here, I’ve had 10 new butterflies in 2 days and only one boy and he is sheltering from the inclement weather.

    I saw the wasp we identified as probably a golden harvester yesterday marching round on my big swan plants .. I know its not meant to have an interest in monarchs but I’m not totally convinced. Anyway it flew away (into my face) unharmed. They are quite beautiful .. but I still don’t quite trust them.



    I saw the article about Ian Knight in Nelson and while I know the Nelson area has had a huge wasp problem for some years, what is happening in my garden – and about 170 others (532 responses to the nationwide survey so far, and 1/3 say what I’m saying) are in a similar situation to mine.

    How can it be wasps, if you’re not even getting eggs?

    We have an instance of a property on one side of the road having a huge amount of caterpillars where on the other side of the road, healthy, pesticide-free plants, no eggs being laid!

    We have reports of no eggs from all over the country while others in the community have normal populations.

    I would be careful not to make too much of a link with decline in North America.

    The only link is the common species. And the fact that people all over the world love the species and would be very sad about it!

    maybe if it is still a problem by next year that would be the time to get serious, because evidence that this is a real problem and not just a blip need to be found before you can start finding out more.

    And how would we do that? What sort of researcher would we need to get on board, in your opinion?



    Just read the comments by Jacqui on this subject on another thread about Forest Ringlets so I suppose this would be the right place to comment so not to go off topic.
    Living in the UK I obviously am very detached from what is going on in New Zealand with the shortage of Monarch and the lack of fertility reported. It could just be weather related as some species just have bad years where they take longer to build up numbers with many possible factors that could be the cause. I would be careful not to make too much of a link with decline in North America. The causes there are easier to spot. Destruction of the overwintering forests in Mexico is one factor. Intensive agriculture in the USA and Mexico and the destruction of more natural habitat by human encroachment being another. The USA is well known for its overuse of Herbicides and Pesticides and the introduction of genetically engineered crops could produce toxic pollen that drifts on to the Milkweeds on the margins and roadsides poisoning larvae. The USA is known to have very lax environmental controls compared to Europe and the overall farming methods are very damaging to all wildlife. Prairie farming monoculture is how it is known locally. The increasing encroachment on the land that is still unspoilt is also a huge factor combined with population growth.
    New Zealand like any other developing nation has pressures on it’s wild areas too but is still fortunate to have a smaller population human wise than many other countries. It will take quite a bit of research to get to the bottom of this suggested lack of fertility but maybe if it is still a problem by next year that would be the time to get serious, because evidence that this is a real problem and not just a blip need to be found before you can start finding out more.

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