Buddleia pests

This topic contains 66 replies, has 14 voices, and was last updated by  Anna 5 years, 10 months ago.

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  • #14137

    NormTwigge
    Keymaster

    Today I noticed the leaves on my Nanho blue buddleia were looking like something was chewing at them. Close inspection revealed an advanced infestation of maggot-like grubs on both sides of the leaves. Putting two and two together I did a search and sure enough they proved to be Cleopus japonicus, a biological control brought in from China to help eradicate the Buddleia davidii which grows rife on riverbanks, roadsides and plantation forest margins.

    The insect is a weevil which lays its eggs on the leaves of buddleia bushes. These hatch out and grow into a maggot-like legless grub, a yellow jelly-like blob which eats away at the leaves, defoliating the plant, stunting its growth, and probably eventually killing it. The grub will grow to about 5 mm in length, and then pupates in a cocoon on the leaf,finally emerging as the adult weevil to mate and start all over again.

    The authorities are more than happy with the results, and advised gardeners to spray their plants if the weevil became troublesome to ornamentals.

    I will post some shots to the Photo section.

Viewing 25 replies - 1 through 25 (of 66 total)
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  • #35592

    Anna
    Participant

    Now that it is spring, and Buddleia bushes are starting new growth, it may pay to check for the weevil. I have found, and got rid of a few adult weevils that may have been over wintering, as well as a small patch of their larvae.
    I found the adults near the fresh new tips mainly. I found about a dozen so far.

    #30726

    Anna
    Participant

    Now a couple of weeks later…my captives have produced eggs, and I have larvae, so it has been interesting to see what to look out for in the garden.
    So far I have been killing any weevils that I find on buddleia in the garden, but it has meant checking every day or so….and removing any leaves that have tiny chew marks. I hope I dont get a bad infestation, as I don’t want to use spray if I can help it.

    #30685

    Anna
    Participant

    Thanks for that Norm.
    I still haven’t seen what the eggs look like, but have a few ‘captives’ that have been mating, so I’m keeping an eye out for any eggs, so I can have a good look at them through the microscope.
    Also I have watched the adult weevils munch away on buddleia leaves, they dig a little hole with their snout, but only through a layer of the leaf, then graze away in the same patch.
    (Actually, they are quite comical little creatures when viewed up close)
    They have very delicate wings that they tuck out of sight unless needed…so you have to be on the look out for them making an escape when studying them.

    #30681

    NormTwigge
    Keymaster

    The larvae of the weevil start on the underside of the leaf at an almost indiscernible size and when larger will move also to the upper side of the leaf where they are more easily seen. The larvae do the damage to the leaves but any adult weevils that are spotted should be dealt with before they can mate or lay eggs.
    The entomologists certainly introduced an efficient biocontrol agent with this one.

    #30678

    Anna
    Participant

    what a pity they have started on Silver Anniversary.
    So far I have managed to find a few weevils and get rid of them before they do too much damage. They tend to congregate near the tips on the buddleia at the moment.
    I have been nipping the tips out of most of my plants to encourage bushy plants, before I let them flower. Its working really well so far, but I need to nip out the tips every few days as they are growing so fast!

    #30669

    Darren
    Participant

    Alas, I was working at Maleme St yesterday and noticed that my Buddleja Silver Anniversary is now being attacked. Previously the weevils had left it alone and I had hoped being a crossing of Buddleja crispa from Sichuan, China and Buddleja loricata from Africa would give it immunity. But while it might be less attractive to the weevil than the other nearby buddlejas, it doesn?t have immunity after all.

    At least there is a solution in Mavrik. It is very low toxicity to non-invertebrates, and it wont bother bees if you spray at dusk after the bees have finished work for the day. By the next day it has dried and won’t affect them at all. I can’t see any reason why the same wouldn’t be true for butterflies. Just don’t plant your buddlejas next to your swanplants and watch out for spray drift.

    #30292

    Darren
    Participant

    For people who don’t like synthetics, and want a “natural” (or cheaper) option, you could always grow some Chrysanthemum cinerariifolium. Pop a tablespoon of flowerheads in a litre of hot water, leave it to brew for an hour or so, add a drip of liquid soap, and use the strained liquid as a spray.

    Seeds are readily available, eg
    http://www.kingsseeds.co.nz/shop/Herbs/Other+Uses/Repels+Animals+or+Insects/Pyrethrum-6430.html

    #30279

    carols
    Participant

    The following info is from the Northland Regional Council website :
    What do the cleopus weevils look like? The adult weevil is grey, about 4mm in length, with the distinctive snout characteristic of weevils.

    The larvae are legless, and appear as yellow, jelly-like blobs on the leaf surface. They have a small black head and grow to about 5mm in length.

    Adults begin egg-laying in spring when temperatures are over 10oC. Eggs are laid into hollowed-out cavities within the leaves and leaf buds. Larvae can be found through to June, if temperatures are warm enough.
    The pupa is small, brown, oval and the size of a lentil. Pupae are commonly found in seed heads, and also on leaves, on the stems and in the leaves at the base of the plant. There are at least three generations per year.

    Damage is easy to see. Adult weevils make small holes, usually only a few millimeters wide. If these feeding holes are recent, the tough epidermis will still be present as a ‘window’.
    Larval damage is similar but much larger and makes silvery areas on the leaf. Larvae also leave little trails of insect ?poop?, known as frass.

    #30277

    Anna
    Participant

    ….back again…Having just had a close look at the weevils, I am now wondering what the adults eat? They have a long snout a bit like an anteater!
    I know the juveniles eat Buddleia, but do the weevils need nectar?

    #30276

    Anna
    Participant

    My captive cleopus japonicus have turned into the adult weevil stage now…..so I can have a good look at the enemy! It will help when I am looking out for them on the buddleia.

    #30256

    Jacqui
    Keymaster

    Sounds hopeful, Darren!

    #30255

    Darren
    Participant

    Five days after spraying with Mavrik the grubs have all turned from yellow to brown, and new leaves are appearing all over the browned off sections of the plant. 🙂

    #30241

    Gilly
    Participant

    I’d hardly do the dousing on a windy day Darren 🙂

    #30238

    Darren
    Participant

    After cutting back I’ve doused my buddleia in talcolm powder

    I hope you were wearing the appropriate Personal Protective Equipment. Talc is magnesium silicate hydroxide. The Pemmissible Exposure Limit (PEL) is 4.0 mg/M3. Inhalation of dust may cause irritation of upper respiratory system. According to its Material Safety Data Sheet, the use of safety eyewear, to protect from dust, is recommended. Recommended to use gloves to protect overly sensitive skin. Use approved respirators/dust masks.Use adequate exhaust ventilation and/or dust collection to keep dust levels below PEL. http://www.talc-powder.com/Talc_powder_msds.pdf

    #30235

    Gilly
    Participant

    I hate sprays and can’t use them cos of my birds. I have cut my buddleia back cruelly and whilst doing this got these awful little bugs all over me… offered them to my various birds and they won’t touch them. After cutting back I’ve doused my buddleia in talcolm powder….. and curiously I have new shoots on them with NO bugs. Interesting my 2 big winter flowering buddleia have not been affected by these bugs as yet.

    #30234

    Charlotte
    Participant

    Gosh Darren your Buddleias really have been hit hard with the Buddleia pest.
    At present we have not seen any sign of the pest. I hope we don’t, but we will be ready.
    Please keep us updated on your progress.

    #30232

    Darren
    Participant

    My local pak’n’save has Yates Mavrik Insect & Mite Spray, which contains 9.6g/litre of tau-fluvalinate, a synthetic pyrethroid.

    I picked up some of that with my groceries and gave them a blast last night. I’ll post the results on here. I have a “before” photo here http://dgedye.files.wordpress.com/2012/04/img_0453.jpg

    #30223

    Gilly
    Participant

    Good idea Anna… go for it 🙂 Bah and twigglesticks to ERMA and Scion. They know not what they do.

    #30221

    Jacqui
    Keymaster
    #30219

    Anna
    Participant

    My Daughter has an old Buddleia at the bottom of her section, and it has been a really good food source for bees and butterflies, but today I had a look at it, and its riddled with the bug. I think there needs to be an article written about it, and forwarded to newspapers, and garden magazines, explaining what it is, and how people who have delighted in having them for the insect life, should be on the lookout for the bug, and how to deal with it.
    Anyone out there good with words??

    #30218

    Darren
    Participant

    The buddleia leaf weevil, Cleopus japonicus, was released in New Zealand by Scion in 2006 as a biological control agent for Buddleja davidii, following approval from the Environmental Risk Management Authority (ERMA). Scion is the trading name for New Zealand Forest Research Institute Limited, a New Zealand Crown Research Institute (CRI).

    #30216

    Gilly
    Participant

    My buddleias are now devastated by these bugs… within a month. Makes me sooo very angry….. all my buddelias are ruined. What happens when these bugs run out of food? Who brought this new bug in?

    #30193

    Charlotte
    Participant

    Oh no Norm that is terrible!!

    At this stage we have not spotted any weevils on our Buddleias.
    We’re waiting for the the last lot of flowering to stop to prune ours back;-)

    #30186

    NormTwigge
    Keymaster

    Inspected my buddleia today and could not spot any weevils – great. But a closer inspection revealed some tiny Cleopus japonicus larvae – #*~!!. So the earlier adults had layed eggs, I had sprayed the bush, and at a later stage the eggs hatched and re-infested the new leaves. Oh well it looks like its out with the spray again. With the bush pruned back hard and not a lot of leaf growth the little blighters may well cause the buddlia’s demise otherwise.

    #30160

    Darren
    Participant

    If Buddleja Silver Anniversary (?Morning Mist?) is immune to Cleopus japonicus I was wondering why that should be.

    The release application noted that
    Cleopus japonicus
    “could attack other Buddleja species in New Zealand, but not B. salvifolia” http://www.epa.govt.nz/Documents/NOR02001-application.pdf

    Buddleja davidii, and Cleopus japonicus are native to Sichuan, China. Buddleja salvifolia however is native to Africa.

    It turns out Buddleja Silver Anniversary is a crossing of Buddleja crispa from Sichuan, China and Buddleja loricata from Africa.

    So it is probably the African Buddleja in its parentage that gives Silver Anniversary its immunity.

Viewing 25 replies - 1 through 25 (of 66 total)

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