Saturday, 20 November 2010

Something's eating my cycads

The flush of new growth on my cycads was disappearing before it even unfurled and the culprit must be found and dealt with.


I don’t mind insects having a bit of a chew here and there. It’s all part of the cycle of life and besides, you can’t have butterflies without caterpillars. But this was different. They threatened to kill the plants if left unchecked. They had declared war. Ugly brown little grubs were all over some of the leaves.

I looked up “eating cycads” on the PACSAO website and discovered that the lovely little butterflies I had been admiring in the garden were the culprits.

"Plants in cultivation and in the wild often fall prey to insect activity and the result can be devastating. Some of these insects have the ability to completely devour a new flush of leaves overnight.

One culprit is a pale blue native butterfly whose larvae feed entirely on cycads. Ironically this small butterfly is known as "Cycad Blue"- Theclinesthes onchya. It is unique in that it is the only Australian butterfly caterpillar that feeds on Cycads.

Spraying is the best option but it has to be done on a daily basis to properly destroy the grubs that constantly keep hatching from tiny pale blue to white coloured eggs.
(their photos - not mine)





The article didn’t say what spray to use. I will not use insecticides in my garden and risk killing the birds I have tried so hard to attract or the beneficial insects that help my garden stay healthy. Couldn't find a natural remedy on the net or in any books I've got. Meanwhile they were chomping away. No time to lose.

Then I remembered Colin Campbell (a local gardening sage) saying a mixture of vinegar and water sprayed on cycads would kill the larvae of something or other. Worth a try!

I tried it. Every day for a week I sprayed the new leaves and it’s worked. I can't see any larvae on them at the moment and I’ve saved most of the cycads’ new growth.
The butterflies are still around so I will need to be vigilant.

They only seem to have attacked the common cycads - Cycas revoluta. My cardboard sago - Zamia furfuracea hasn't been affected. maybe because it's a different species.

22 comments:

  1. So far I've been lucky with my Cycas revoluta ... but then I haven't seen those Cycad Blue butterflies around here. If I ever do, I'll remember your great hint courtesy of Colin. Love your Zamia ... that's one plant I've always wanted and haven't yet got.

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  2. You could hang some dead grubs on a fence nearby or make a mobile to hang over the cycads with dead grubs on it...to frighten them away. :-) I am going to try that spray on my raspberries which have those shield bugs all over them. They are clustering on the little fruit and will suck all the goodness out of them.

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  3. Isn't there always something to give us trouble? The butterflies are beautiful, but the damage the grubs do isn't. I'm glad you were able to find a remedy that helped.

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  4. He He Hazel - dead grubs aren't as pretty as snail shells.
    I'm guessing it's the acid in the vinegar that does the job. Mild enough not to hurt the plant but enough to kill the caterpillars.

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  5. What a clever pup you are Missy. I love watching the gardening shows too and know Colin Campbell via them. I don't think the cycads would grow for me here but there are a species that grow along the sth coast called budawangs or is that burrawangs, I can't remember without looking it up. You can see them dotted through the bush especially around bateman's bay. Very pretty and very slow growing so the biggest ones are real old.

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  6. They seem to be taking quite a bite. I hope you get to solve the problem soon

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  7. You won this war! Congratulations! Vinegar is a wonderful thing, isn't it?

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  8. Another method is to put a bounty on those litte larva's head. My grandson's will take care of your problem quickly by catching them and placing them in a jar... only 25cents per larva. Of course, you will also have to pay for the airfare. Better stay with the vinegar solution. :)

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  9. The vinegar solution has helped you out, what a good pest control. Vinegar is such a miracle worker all over the house.

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  10. I have Cycad Blue in my garden. But I don't have any Cycad. They have been disturbing my basil which I intend to remove soon. Glad you have resolved your Cycad and Cycad Blue issue.

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  11. Missy 1 - bugs 0

    nice score

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  12. Am wanting to try the vinegar cure - does it matter if it's brown or white vinegar? What is the ratio of vinegar to water? This sounds wonderful - and it's natural! Hope to hear from you soon Julie

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  13. I use the cheapest homebrand vinegar (any type will do)about 50/50 with water in a spray bottle. They returned again this year. The vinegar doesn't kill the butterlies so they still lay eggs but will kill the lavae - you have to keep watching because they will come back.

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  14. My Cycad's fronds are practically falling off. I had a closer inspection of the fallen frond and found it waas full of holes. I then inspected the area where the frond fell out and saw three "things". The first two were 2 different types of black insects and the third was quite a fat white worm which was the prime cause of the holes in my fronds. I managed to get a sample of each of the insects and will be taking these down, along with a fallen frond to one of our local botanists for analysis. In the interim, I mixed up a concoction of water and vinegar as you directed, and poured it onto an area of my cycad, It was quite amazing, because almost instantly, the smaller of the insects stated to leave the plant. I'm not quite sure if the vinegar story is going to work, as the infestation seems to be at the heart of the plant and does not manifest itself on the fronds. Other fronds on this plant are starting to go brown, and I would believe the plant will die. I am charging my batteries for my camera to take a pic, which will probably only be ready for posting tomorrow. Any suggestions and/or advice would really be appreciated, as I would hate to lose this magnificant plant.

    I can also be contacted via my email: flicker@iafrica.com

    Kind regards

    Robert (Port Elizabeth - South Africa)

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  15. Thanks for the Vinegar solution Missy. I have waited patiently for my new fonds to open after all the leaves turning brown last year, only to find them shrivelled and chewed by these nasty brown bugs. I am off to spray the little buggers now !

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  16. Thanks Missy you just saved me a fortune on chemicals to kill the blighters eating my cycad's vinegar works a treat.

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  17. The vinegar solution worked for me once before and now the little monsters are back again, I'd forgotten the ratio of water/vinegar. Many thanks for the solution' to my problem. I bet your garden is just gorgeous....

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  18. Thank you so much for this info. I have been spraying my 2 dozen cycads with pyrethrum for a couple of weeks now. It has been working but costs a lot and also destroys other insects. I will be hitting them with good old vinegar and water in the morning.
    Raelene

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  19. Hello everyone.. I'm just learning about gardening & have been having a lot of trouble with my beautiful Cycad..I have just sprayed it with Vinegar 7 Water and am keeping my fingers crossed as I would hate to lose the plant.. Looking forward to learning more from you.. Have a wonderful day

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  20. The dreaded brown grubs have attacked the new fronds on two of my cycads - so I'm guessing it's only a matter of time before the others are affected as well. I had tried Pest Oil, with no success, so now I've just made up a solution of vinegar and water, and I'm off to declare war on them right now... thanks for the tip. It's quite windy here today, and I normally won't spray when it's windy, but this calls for drastic action, and I can't wait!!
    Thanks again... Del

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  21. Hi Missy, have faced the dreaded brown grubs for 2 years now which have obliterated new growth as mentioned "overnight." Now thanks to you I can counter attack and control those pesky critters.... Will keep you advised, Ardy

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  22. OK your a dog. Your always in the yard. You lie under the cycads on warm days. Have you seen where theses bugs go in between butterfly and grub. Can we attack them at any other stage of their life cycle?

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