British Columbia: Sawfly larvae

Discussion in 'Outdoor Gardening in the Pacific Northwest' started by Seastcott, May 30, 2011.

  1. Seastcott

    Seastcott Member

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    I have a problem with sawfly larvae on my gooseberries and currants, (it is a small green worm-like insect with a voracious appetite) does any know any way to get rid of them as they are (very quickly) eating my plants and leaving just sticks. I was not able to hand pick them off last year and insecticidal soap did not work, I was hoping for a predatory insect rather than poison if possible. Thank you.
     
  2. Sundrop

    Sundrop Well-Known Member

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    Spray with Btk.
     
  3. Seastcott

    Seastcott Member

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    What is Btk? and can I buy it at most garden centres?
     
  4. Lysichiton

    Lysichiton Active Member

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    I think you need an accurate identification, to be sure of the pest & the control. I recalled that SAWFLY larvae are not controlled by BTK. They are not "caterpillars" of moths or butterflies. There are a lot of references on the net to that effect when I just checked. Insecticidal soap should work. Perhaps you could check out the formulation & try it again. Just a thought.
     
  5. Seastcott

    Seastcott Member

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    Thank you, I sprayed it with soapy water, to try and control it before my entire plants are destroyed (I have 4) I will try another insecticidal soap and see if it works, I was really hoping for a predatory insect to just eat them and take care of it for me....
     
  6. Lysichiton

    Lysichiton Active Member

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    Well, sometimes they don't come along in time for us impatient gardeners. I had to deal with "army worms" (caterpillars at battalion strength) & in the end just gave up growing Aquilegia in my front yard for a couple of years as the easiest control. It worked.

    If you make sure there is a water source & moist clay available, I bet that "mud wasps" & a variety of other Hymenopterous insects will make their home in your yard. Mind you I have to explain to my family that these elegant bugs are not scavengers or as aggresive as Yellowjackets. The insects must get through a pound or two of clay every year from the pond margin in my yard. I buy more & re-pack the spaces where they mine it - my family thinks I am nuts. Harmless, but strange. I don't care.
     
  7. Seastcott

    Seastcott Member

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    Thank you very much for the information, I may have to wait a few years before I can create a water feature with clay for mud wasps, as I have small kids, but for sure I will keep it in mind for the future. I guess for now insecticidal soap is the only answer, that or get rid of the gooseberries and currants altogether.
     
  8. Thean

    Thean Active Member 10 Years

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    Good Morning Seastcott, fellow gardeners,
    Sawfly is a perennial problem for me. Insecticidal soap works by plugging up the breathing holes on the insect. So you must really coat the larvae. Mama is a neat freak and lays her eggs in neat rows on the the veins on the underside of the leaves. The eggs are evenly spaced. Hence when the eggs hatch, you will notice tiny holes on the affected leaves. I merely remove these leaves and throw them to my goldfishes. If I miss this stage, I spray since I do not have the patient of Job to pick them off one by one. Once they have consumed their home base (the leaf on each mama laid her eggs) they merely move to the next leaves. So spot spraying is all I need to do.
    For me, sawfly is extremely easy to deal with. My main problems are Black Currant Weevils and Currant Fruit Flies. Tips on controlling these are much appreciated.
    Peace
    Thean
    PS. I was told chickens and ducks do a fine job of controlling the three insects (and more) but the City's bylaws forbid me from having any.
     
  9. Sundrop

    Sundrop Well-Known Member

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    Unfortunately there is a lot of conflicting even contradictory information about almost everything on the Internet. The whatever-it-was on my currant plants looked exactly as on the picture here: http://www.gardenworldimages.com/Details.aspx?ID=31042&TypeID=1&searchtype=&contributor=0&licenses=1,2&sort=REL&cdonly=False&mronly=False. And Btk definitely worked on them. What is very important is to check the expiry date on the product (it is not a chemical spray) and give the caterpillars enough time to feed on the sprayed leaves, before rain will wash the spray away.
    Anyhow I moved my plants to the spot in my garden where they have much more favourable conditions to grow now and don't have this problem any more.
     
  10. Lysichiton

    Lysichiton Active Member

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    ...and my blackcurrant has a horrible case of blackfly for the second year in a row. I shall have to resort to insecticidal soap. No winning eh?
     
  11. Seastcott

    Seastcott Member

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    Wow, thanks for the information. Growing veggies and fruits is new for me, so I am encountering all sorts of new things. The Gooseberry sawfly I have is more green, and they don't really have the black spots but they sure can do a lot of damage. Last year they stripped one of my gooseberries clean of all of its leaves. The plants are only a few years old, so I was concerned the attack would kill them. I will continue to try insecticidal soap and try and do more research on nematodes and see if there is one that will kill the sawfly larvae, if that is indeed what I have on my plant.
     
  12. Sundrop

    Sundrop Well-Known Member

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    Seastcott, could you post a picture of your Gooseberry sawfly larvae?
    Since, as you wrote, you are new to growing veggies and fruits, you may be interested what are the growing preferences of currants and gooseberries (Ribes). Ribes are native to cooler climates of the northern hemisphere. They need good air circulation and moist (but not wet), cool soils, rich in organic matter, with good drainage, at least 50 cm deep. They prefer soil on the slightly acidic side. They require a long chilling period and are intolerant of summer heat. They are shade tolerant, in fact they should be planted in dappled shade (among fruit trees) or in the afternoon shade, especially in warmer climates. They greatly benefit from mulching with a thick layer of organic matter to ensure evenly moist, cool conditions at the roots. If you can afford your plants this kind of conditions you will not have to worry too much about insects and diseases.

    Thean, how the damage by Black Currant Weevils and Currant Fruit Flies in your garden looks like?

    One more question Seastcott. Do you know how many prolegs your larvae have?
     
    Last edited by a moderator: Jun 2, 2011
  13. Seastcott

    Seastcott Member

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    I will try and get a decent picture and post it tomorrow, what are the pro-legs (the front ones?). My gooseberries and currants are situated along a fence on the south eastern side of our property, so they get a some shade, they are in fairly decent soil (I think) and I used bark mulch over top of a weed barrier, they are located with 5 blueberry plants. Maybe I should have added some mushroom manure to top dress around the plants? or is the bark mulch sufficient?
     
  14. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    Another option is to put up a bird feeder close by. Birds in the queue for the feeder will feast on the sawfly larvae while they're waiting.
     
  15. Sundrop

    Sundrop Well-Known Member

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    Chickadees love those little caterpillars!

    As for the mulch I much prefer a mix of what I have on hand: grass clippings (I don't use any whatever-cides), organic straw, compost, may be a very little of organic manure, too. I also sow cover crops or green manures in my garden and around my fruit bushes (living mulch). This kind of mulch not only keeps the moisture and temperature in the soil even but also supply home and food for the soil organisms, that in turn feed the plants.

    Proleg Larvae of sawflies have 6 to 9 pairs of prolegs, lepidopterous larvae have 5 or less.
     
  16. Thean

    Thean Active Member 10 Years

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    Good Morning Sundrop,
    There is a larva in each berry. Most people here point to the Currant Fruit Fly (CFF) as the culprit. Actually both the Black Currant Weevil (BCW) and CFF are involved. In my yard the BCW adults can be seen by late April and they start laying eggs even before the CFF emerges in late May or early June. BCW deposit her eggs on the peduncle and the larvae tunnel down into the berries. This year, CFF is just starting to show herself. She lays her eggs directly under the skin of the berries. In both cases the berries ripen prematurely and drop off at the slightest agitation. The larvae between the two are easily identified even with the naked eye since one is a weevil and the other is a fly. In some years I lost 100% of the crop. I picked up all the berries and put them in milk jars and placed them in the sun to cook. (Sorry for being a sadist.) There were years when I pick every berry off the bushes instead of waiting for them to fall. But that did not put any dent in the population. I have tried yellow sticky traps too. The only thing that worked so far is pesticide application. Any tips on biological control is most appreciated.
    Peace
    Thean
     
  17. Sundrop

    Sundrop Well-Known Member

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    Hello Thean,
    Thanks for the information. After reading this I run to my garden anxious to see how my already developing berries look like, but they seem to be ok. I never paid too close attention to the berries before, didn't know they could be infested!
    As for your problem, I don't know of any quick solutions. The only advice I can give is, try to ensure your plants grow in conditions they need to perform well so they are strong enough to develop internal barriers against pests and diseases. Gardenscape for beneficials http://www.wildaboutgardening.org/en/attracting/section5/index.htm . Try to create in your yard and garden as biodiverse environment as you can so the beneficials will take care of your bugs. This applies not only to the environment above the soil surface but, what is usually forgotten, also inside the soil. "Many organisms, including pest insects associated with both perennial and annual crops, spend part of their life cycle in the soil. A diverse soil ecology maintained with regular additions of organic matter helps to regulate populations of both pest and beneficial organisms." - https://attra.ncat.org/attra-pub/farmscape.html. You can work organic matter into the soil, or apply it on top in the form of mulch.
     
  18. Seastcott

    Seastcott Member

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    I wanted to thank everyone for your help, time and replies, when I went outside to take pictures of my sawfly larvae, it appears for now they have been eradicated. Although my plants are looking sort of sick from the amount of soap I used (a combination of both insecticidal soap and regular dish soap), it appears to have done the job. So for now thank you everyone for all of your advice, I will for sure use it to help with my problem in the future, as I am sure they will be back. And when they return, I will post some pictures of them. So for now - Happy gardening....
     
  19. Thean

    Thean Active Member 10 Years

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    Good Morning Sundrop,
    Thanks for your tips. I practice IPM for ages. I do my part but if others in my neighbourhood is not, the problem will never go away. As I see it, there are only two predators of BCW and CFF in my area. They are birds and spiders.

    Good Morning Seastcott,
    Watch out. I can get as many as three generations in Edmonton. My first round with Sawfly is just over and I'm on the lookout for the second round.

    Peace
    Thean
     

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