Threat to Tweedia!

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  • #14898


    How do you feel about Environment Waikato importing a beetle to destroy moth plant and tweedia?

    I subscribe to the "Get Growing" email from NZ Gardener ( and the latest edition says that Environment Waikato will soon apply to the Environmental Risk Management Authority for permission to introduce a biological control agent to attack moth plant and to help control it.

    Richard Hill from Plant and Food will be writing the application for Landcare Research, the science advisors to Environment Waikato. The research to determine whether this root-feeding beetle is safe to be introduced has been completed. It shows that the beetle is restricted to a very narrow range of host plants, and that no native species are at risk. Swan plants (which are closely-related to moth plants) are also immune from attack. However, the closest relative to moth plant present in New Zealand is tweedia, an old-fashioned garden ornamental, and the tests show that the beetle is likely to attack tweedia too.

    Richard Hill’s role is to present the case for and against introduction. He wants to find out whether possible damage to tweedia would be a significant concern to the New Zealand public so that ERMA can weigh up the costs and benefits of introducing the beetle.

    email Richard with Tweedia in the subject line to have your say!

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  • #45042


    Moth plants are weeds here and only danaus erippus are safe & best control for moth plants. Caterpillars of danaus erippus eat moth plants, and unlikely to become extinction in NZ as long as there are moth plants. Chance the Monarch butterfly being biggest butterflies here are dominant butterfly over smaller danaus erippus. – See more at:

    But these Southern Monarch butterflies danaus erippus were not been imported to control our pesty Moth plants.
    No promise as moth plants are very tough plants and the beetles cannot control these moth plants very well as caterpillars of Southern Monarch butterflies, would.

    Southern Monarch butterfly caterpillars eat much faster and eat more leaves, cause more damages to Moth plants than beetles.
    While beetles eat little out of Moth plant leaves.
    Unless we import Southern Monarch butterfly caterpillars to NZ to control Moth plants, the Moth plants will always win and cannot disappear.
    So useless little beetles.




    Hi Darren,
    I agree with you.
    But Richard must be very careful as there are bad pest colaspis beetles that look like moth-eating colaspis argentinsis.

    He need great patience in ID the colaspis argentinsis from alike colaspis beetles that look like c. argentinsis.

    Africanized honeybees are difficult to tell apart from common european honeybees.

    When colaspis beetles were released on moth plants, they will take about 5-10 years to increase their numbers and they might flies to houses at nights, like moths to lights.

    They are likely to be released on Barrier Island and maybe in parks in Auckland.

    There is no promise that colaspis argentinesis will eat moth plants only and nothing else.

    We have to wait & see.

    Jenny Khoo (ERMA manager) is working on applications for importations of colaspis argentinsis and danaus erippus.




    I guess we will have to read the application to ERMA for more details, but knowing that colaspis argentinensis has been tested on G. fruticosus is certainly some comfort.

    Its also important to bear in mind that colaspis argentinensis will not totally eradicate its target moth plant just as it has not eradicated it in Argentina. An equilibrium will be reached. But hopefully the beetles will knock it back and make it less invasive. Since C. argentinensis won’t be able to eliminate its target, it is pretty safe to assume it won’t be able to eliminate non-target species either.For myself I would be happy to to trade minor damage to tweedia for major damage to mothplant.

    I just wish there was more information about C. argentinensis readily available. A google search for “colaspis argentinensis” gave me zero results. A search for +colaspis & +argentinensis gave me 77 results, most of which appear to be in Spanish (which is logical given its origin, but not of much use to me!). It is rather hard to have an informed debate when information is so hard to come by.

    (And Clinton you are certainly entitled to your opinions, but an opinion remains an opinion no matter how emphatically it is stated.)



    Competition between Monarch butterflies and danaus erippus over swan plants will not happen, as there are lot of feral swan plants over northern North Island in zone 10 for both species.

    In Australia, Monarch butterflies putted up with competition with Orange wanderer butterflies (danaus genutia), Lesser Wanderer butterflies (danaus chrysippus), Brown wanderer butterflies (danaus philene), Blue tiger butterflies (danaus hamata), very well. Monarch butterflies are still common.

    In southern USA, Monarch butterflies flies with Queen butterflies ( danaus gilippus) and Soldier butterflies(danaus eresimus) and their caterpillars eat together on same plants.

    This shown me Monarch butterflies are capable of put up with competition with danaus erippus over swan plants in NZ.



    OK, but if we don’t import danaus erippus to eat moth plants and there are no suitable colaspis beetles that eat moth plants only and nothing esle, we have to face the problem…How can we try to get rid of pest moth plants withOUT insects ???

    Danaus erippus will not cause competition over swan plants.
    In USA (native country of Monarch butterflies) the caterpillars of both Queen butterflies (danaus gilippus) and Monarch butterflies feeds on same milkweeds.
    On 2004 I had seen caterillars of both Monarch butterfly and Lesser Wanderer butterfly, feeding together from same swan plants. In Australia both Monarch butterflies and few danaus butterflies as Blue tiger, Lesser Wanderer, Crow butterflies get along well.
    Danaus erippus are NOT likely to cause problems with Monarch butterflies. They will learn to get along with other each.
    Monarch butterflies will remain common, no matter how hard they face competition, and Monarch butterflies will NEVER disappear through competition with danaus erippus over swan plants. Monarch butterflies lives in both eastern South Island and entirely North Island, while danaus erippus might be confined to lives in Kaitaia to Thames. Monarch butterflies WILL ALWAYS WINS.

    Trying to find moth plant-eating suitable colaspis bettles in bush in southern South America, is like find a pin in haystack…unlike easily-to-find danaus erippus, the beetles are hard to find, you have to have a great patience in looking for beetles in moth plants.

    To control the moth plants which are pest here, you will need about 500 to 1,000 beetles (via 200-500 danaus erippus pupaes)
    The all people in NZ will say “no” to colaspis beetles, but some people might say “yes’ to danaus erippus.

    Danaus erippus flies the longer distances and faster fliers than colaspis beetles, and always get moth plants first before beetles. Caterpillars of danaus erippus are bigger and eat more moth plants than beetles and their grubs.

    Grubs of moth plant-eating colaspis beetles, might switch to eat other plants and tweedia or beetles might get a taste for tweedia and become pest themselves.

    Please be very careful with importation of colaspis beetles.



    Once again you have raised many great points to discuss.

    If it was introduced, Danaus erippus would be quarantined to make sure no parasites or diseases were introduced, so there would be no risk to plexippus on this front.? Landcare Research is thinking carefully about the likely importance of much more subtle interactions between a new monarch and insects already present in New Zealand, including competition for swan plants.?

    Insects accumulate toxins not to poison birds but to be distasteful. Having tried them once the birds then avoid the insects in the future, and can teach their young to do the same. Insects that use this strategy do not seriously affect the life span of their predators.

    There are plenty of beetles that are specific to one, or a just a few host plants, and many beetles have been safely introduced to New Zealand for weed control – successful conrtol of ragwort by ragwort flea beetle is a case in point. There are over 40 species of Colaspis in the world. Some are indeed pests, but they are largely specialist pests. For example, Colaspis pini is a pest of pine trees, but only attacks pines. Some are pests because adult beetles feed on the foliage or fruit of valued plants (such as the Colaspis that is a pest on banana). Landcare Research recognised this possiblity, but experiments show that adult Colaspis argentinensis have the same narrow host range as the larvae. The pest status of some Colaspis species does not negate the safety and value of others.

    Darren – I used the words ‘could not’ in one statement. You are correct. I should have used the words ‘did not’, as I was reporting the experimental study. The tests will be reported in full in the application, but I can tell you that G. fruticosus was tested but not G. physocarpa. The practice of choosing one species to represent a genus of plants in safety-testing is not unusual. Asclepias and Gomphocarpus are still in a separate tribe from tweedia and moth plant.



    I agree with you, Bernie, but I had never seen caterpillars of Monarch butterfly on moth plants in wild all my life, but moth plants are of help if caterpillars run out of swan plants.
    But moth plants are pest, and difficult to control.
    Danaus erippus may be suitable & safe control for moth plants.
    Caterpillars of danaus erippus eats moth plants.



    Just to clear up a point,I have bred monarchs from egg to adult on moth plant and if my memory serves me correctly,I have only ever had one egg actually laid on moth plant.This was when it was actually touching a milkweed plant in my greenhouse and I just assumed that the female had “missed” and laid on the moth plant by mistake.



    I am agree with Darren about colaspis beetles would be trialled on moth plants, tweedias, and swan plants and milkweeds and be studied on their willing or not willing to eat swan plants & tweedias & milkweeds, pine, soybean.

    I had researched about colaspis beetles and found the colaspis beetles are pests and had caused damages to pine trees and grapes and banana plants and sugarcanes, beans, peas, soybeans, tomatoes and potatoes, corns.
    Larvas (grubs) of colaspis beetles eat roots of plants above, cause plants to fell or have stunted growth.

    Colaspia beetles are difficult pests for people to control, through spraying & digging, trapping, with sticky lures.

    Most colaspis beetles are flighted and have dull brown colour on body & wings and capable of flying for long distances.

    I feel it is not good idea importing colaspis beetles to NZ.
    Colaspis beetles have very high risk of becoming pest here.



    Richard thank you for joining our forum and giving us a chance to be part of the consultation for this project.

    In my posting and email I stated that “caterpillars of The Monarch Butterfly eat mothplant

    Monarchs lay on members of the Gomphocarpus and Aclepias genra, which are members of the Asclepiadoideae Subfamily, along with Araujia Genus. While Monarch caterpillars eat moth plant, I am not sure if they lay on it. If as you have said they do not lay on it, then I concede that is a point in the colaspis beetles’ favour.

    You also stated

    The technique is based on the idea that closely-related plants will be more acceptable to an insect with a narrow host range than less related plants.

    Fair enough, I understand that. My worry is that the relatedness of different plants is still being clarified and debated. For example in 2003 the Angiosperm Phylogeny Group revised the Asclepiadaceae family and made it a sub-family in the Apocynaceae family. Swan plant itself is the subject of an ongoing debate as to whether it should be known as Gomphocarpus fruticosus or Asclepias fruticosa. The same is true of Asclepias physocarpa/Gomphocarpus physocarpus, another common monarch hostplant in NZ.

    Given this uncertainty, I would be happier knowing that colaspis beetles had been trialled on Gomphocarpus fruticosus/Asclepias fruticosa and Asclepias physocarpa/Gomphocarpus physocarpus, and that their claimed immunity is not merely based on current theories of those plants relatedness to Araujia sericifera or Araujia hortorum. Can you clarify that point for me please?

    You have also pointed out that Barron (2007)shows that Admiral decline is not solely due to Pteromalus puparum.
    I did not mean to imply that it was, and our factsheet on nettles notes that:

    A number of reasons have been suggested for its decline such as the parasite wasps Echthromorpha intricatoria that came here from Australia in the 1900s, and Pteromalus puparum, which was deliberately introduced in 1933 to control the Cabbage White Butterfly.

    Another possible reason is a reduction in the availability of their food plants.

    My mention of Pteromalus puparum was intended as example of collateral damage, not as the Red Admiral’s only problem.



    It is not just a question of introduced species eating out a host, it is also a question of whether they might change their nature, breeding and so on in a new environment. Richard says “Asclepias curussavica and swan plant are less closely-related to moth plant (same tribe) and could not support beetle development.” I would like to know why the words “could not” are used here. Has there been any further data supplied by Richard?



    Hi Terry,
    Moth plants are weeds here and only danaus erippus are safe & best control for moth plants.
    Caterpillars of danaus erippus eat moth plants, and unlikely to become extinction in NZ as long as there are moth plants.
    Chance the Monarch butterfly being biggest butterflies here are dominant butterfly over smaller danaus erippus.

    Darren is absolutely right, we have to be very cautious & careful in importing insects as colaspis beetles which might eat swan plants & tweedias once they run out of moth plants.

    Like Darren, my first response is to urge extreme caution.



    You are absolutely right Terry. There are numerous reasons why people can not and must not bring in new species whenever they feel like. For example the Cat, Dog, Deer, Ferret, Goat, Hedgehog, Mouse, Pig, Possum, Rabbit, Rat, Stoat, Himalayan tahr, Weasel, German wasp, Common wasp, Asian paper wasp, Varroa destructor, Sea squirt, Grass carp, Gambusia, Rudd, Catfish, and Trout might have been “healthy & free of diseases and parasitoids” when they were imported, but that didn’t stop them becoming an invasive species once they got here!

    I am not anti Colaspis per se, and to me biological control is preferable to the ususal “kiwi way’, which is to dump tons of 2,4,5-T, or 10-80 on any problems. But one can always stop spraying, once a new species is released it is usually here to stay. So my first response is to urge extreme caution.




    I would be very surprised if just anyone can import Danaus erippus in to NZ, apart from pupae for use in Tropical Butterfly exhibitions, with of course the resultant import licence and high biosecurity measures in place at these exhibitions. Just because the pupae were deemed to be free from parasites and diseases would not be a preventative to just anyone importing what they liked and then releasing it in to the environment with possible catastrophic results. It’s all well and good to make bland statements like there are enough Swan plants to feed both species, but one species may become dominant at the expense of the other, you can never tell what the result will be so it’s best to be cautious. New Zealand has enough bad examples from history to prove what I have just stated is true. Now I am not saying I am definitely right on this one, I am sure someone else on the forum will give us an accurate answer, but if I am wrong, what is there to stop me from sending someone a batch of Large White eggs, free of course from parasites and disease in to NZ?



    Slow down, Danaus erippus can be imported to New Zealand, proved the pupaes are free of parasitoids and diseases.
    Pupaes are best stage of butterfly life, for import to NZ.
    Both Monarch butterfly and danaus erippus cannot hybridize with other each. Chance we get healthy pupaes only of danaus erippus.
    I will not agree about beetles as there are NO beetles with low risk of become pests in NZ. Exotic beetles are NO-NO to import to NZ. They have high risk of become pests here.
    Butterflies are low risk animals to import as long as they are healthy & free of diseases and parasitoids.
    Please don’t import Colaspis (beetles) here, also beetles that feed on moth plants are likely to be bright-coloured & poisonous and flightless, this will hurt our native birds when they eat exotic beetles you import & dies of being poisoned.
    Being flightless they cannot control the moth plants as well as danaus erippus.
    So danaus erippus is the BEST & SAFEST control of moth plants and look like Monarch butterflies, so this do not hurt our native birds that leave them alone.
    We had lot of exotic beetles that are pests here in NZ.
    I had carpet beetles (pest) in my drawers.

    We have enough swan plants and feral swan plants for feed both danaus erippus and Monarch butterfly caterpillars, and Monarch butterflies will be still around here for us members to see, flying together with danaus erippus, over buddleias.

    Yours Sincerely



    Richard, damn, I was so looking forward to another Monarch relative coming here.
    Anyway, sounds like its a foregone conclusion now but I still have a question:
    I’m assuming you already know that the Northern monarch (Danaus plexippus) doesn’t lay its eggs on Moth plant. The caterpillars actually have to be put on it for the leaves to be eaten.
    So, does the Southern monarch (Danaus erippus) lay her eggs directly on moth plant in South america or not?
    If she does, then moth plant could be downsized in population fairly quickly if she was introduced here.



    Thank you all for your contributions to this discussion so far. I am delighted to be able to comment on the many good points you have raised. Thanks to Darren for posting the Newsletter article. It sets the scene for what is the next logical step in this project.

    Perhaps I should deal with the Danaus erippus question first. As Lynley said in the newsletter, this monarch was originally a frontrunner in the search for a biological control agent for moth plant. Further research in Argentina suggested that the host range was not as narrow as was originally thought, and that related plants such as swan plant might be at risk in New Zealand. Landcare Research were also mindful of a theoretical risk of changing the balance of Danaus plexippus populations if the new monarch shared the same local predators, parasitoids and diseases. No-one wants to adversely affect monarchs. For the time being this monarch has dropped down the priority list for research beacause there are clearly safer options.

    As Monarch enthusiasts, you are fully aware that insects can be restricted to a single host. In fact, a significant proportion of all insect species that feed on plants have a very narrow host range. Biological control agents for weeds are selected from amongst these, and the beetle that feeds in the roots of moth plant is a case in point.

    The trick is ? how do you prove it? Experimental protocols to predict the host range of biological control agents have been in place for over 40 years. The performance of these protocols is monitored closely, and in hundreds of projects undertaken worldwide, not once has there been environmental damage resulting from a failure of the protocols.

    The technique is based on the idea that closely-related plants will be more acceptable to an insect with a narrow host range than less related plants. You know this is so for monarchs. In this case, tweedia and moth plant are very closely-related (in the same sub-tribe), and the beetle completed development in the roots of both. The hierarchy of plants goes ? family, sub-family, tribe, sub-tribe, genus, species. Asclepias curussavica and swan plant are less closely-related to moth plant (same tribe) and could not support beetle development. If you think of this like a family tree, tweedia and moth plant would be first cousins (sharing a grandfather), while Asclepias and swan plant would be second cousins to moth plant (sharing a great grandfather). Not close at all.

    The final referee of the experimental data will be ERMA, and an application to release Colaspis will be presented to them in July. I will post here when it is submitted, and you can read the final application and make submissions to ERMA then if you wish.

    I should stress that the possible risk to tweedia is a worst case scenario. It is based on eat-or-die laboratory tests under very favourable conditions, and might not be common at all in the field.

    That is probably enough for now, but I will post again when questions arise.



    I checked in my computer about danaus erippus and found a website with a male danaus erippus in La Plata, Argentina, in latitude 36 S which is same latitude as Kaitaia, and they may fly south to latitude 40 S during summertime.

    Caterpillars & pupaes of danaus erippus are similar to pupaes & caterpillars of Monarch butterfly.

    Danaus erippus look similar to Monarch butterfly, but had white lines by black veins on hindwings and orange (instead of black) on inner margin of forewings.

    But details needed in telling the caterpillars and pupaes of danaus erippus from caterpillars & pupaes of Monarch butterfly.




    This map shows the world-wide distribution of subspecies D. plexippus plexippus, and the range of D. plexippus erippus (as they were known as prior to 1984)

    see also
    Brower, Andrew V. Z. 2007. Danaus plexippus (L. 1758). The Monarch Butterfly. Version 02 August 2007 (under construction). in The Tree of Life Web Project,
    Tree of Life Web Project. 2008. Danaus erippus (Cramer 1775). The Southern Monarch. Version 13 November 2008 (temporary). in The Tree of Life Web Project,



    Hi Marigold

    No they’re not the same. Danaus erippus is the southern Monarch (from South America) whereas D. gilippus is known by the common name of the Queen, and I think found in North America. This excerpt from Wikipedia:

    Following the review of Smith et al. (2005), 12 species (of the genus Danaus) are provisionally accepted…

    Danaus affinis (Fabricius, 1775) ? Malay Tiger
    Danaus chrysippus (Linnaeus, 1758) ? Plain Tiger, Common Tiger, or African Queen
    Danaus cleophile (Godart, 1819) ? Jamaican Monarch
    Danaus dorippus (Klug, 1845) ? Dorippus Tiger (formerly included in D. chrysippus)
    Danaus eresimus (Cramer, 1777) ? Soldier (butterfly), Tropic Queen, includes D. plexaure
    Danaus erippus (Cramer, 1775) ? Southern Monarch
    Danaus genutia (Cramer, 1779) ? Common Tiger, Indian Monarch, or Orange Tiger
    Danaus gilippus (Cramer, 1775) ? Queen (Butterfly)
    Danaus ismare (Cramer, 1780) ? Ismare Tiger
    Danaus melanippus (Cramer, 1777) ? White Tiger, Common Tiger, or Eastern Common Tiger
    Danaus petilia (Stoll, 1790) ? Lesser Wanderer
    Danaus plexippus (Linnaeus, 1758) ? Monarch (butterfly) or Wanderer

    Hope that helps!




    I Googled Danaus erippus it came up as Danaus gilippus are these the same. I got The complete encyclopedia of butterflies out of the library and Danaus erippus is not in it, but Danaus gilippus is with it’s black markings edged in white on it’s wings. Marigold



    If caterpillars of danaus erippus eats the leaves of moth plants, then without leaves or too few leaves, the growth of plants become slow and numbers of fruits decrease.

    Both moth plants and danaus erippus lives in South America at same latitude as New Zealand, this means danaus erippus have similar hardiness as Monarch butterflies.

    I vote for Best moth plant control: Danaus erippus.

    I do not agree about beetles and I do not want beetles to be imported to New Zealand.

    Danaus erippus covers wider distance and able to fly means they control moth plants from Kaitaia to Thames.
    Being a butterfly, danaus erippus are harmless insects.

    Members, please vote for danaus erippus only as control of moth plants.




    Danaus erippus make good control for our moth plants and since they are butterflies, I think good idea to import danaus erippus to NZ to control moth plants.




    It’s ironic that I find the idea of my swanplants being eaten by Danaus erippus exciting, yet I am appalled at the thought of them being attacked by a root eating beetle. My prejudice is obvious.

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