I’m writing this post in response to the disaster that I have started seeing in the last few years. The culprit is called Cycad Blue Butterfly. It never used to be like this but in the last few years it has gone to a problem that can’t been ignored.
This is a problem for me given that I prefer not to use poisons for my own health. But cycad’s will not survive without a plan on how to care for them. I don’t know how badly they are affected in other areas, in SE Queensland and Nthn NSW it is quite bad, but viewing fact sheets to find out what it was, I noticed that they are also getting attacked there.
The problem explained. The cycad blue butterfly attacks the fresh growth as it is unfolding. You have to get onto it as soon as you can. Once it has been affected it will continue to show the ugly damaged growth once it has turned into adult foliage, and is too tough for the young caterpillars to chew.
You will notice a huge activity of blue-grey butterflies hovering around your cycad. They leave behind larvae. It is the larvae that will chew on the young fresh leaflets. They also attack the local native cycad species Lepizomia peroffskyana. In this case they will tunnel down the stem of the fresh leaf shoots, further damaging the soft tissue. They are not as extreme with this species, meaning they don’t attack every specimen, but Cycas revoluta the main focus of the butterfly, not one specimen I have seen has been left undamaged.
If the larvae are left to attack every flush of growth that occurs on a cycad they can deprive it of the vital chlorophyll the plants need to sustain themselves, and will lead to death.
The important question is do you want to see such a stately long lived plant that might be anything from 20 years old, in your garden die. So!
The plan. Spraying cannot not be avoided. From reading around Confidor or Imadoclorprid as the chemical is known is a systemic insecticide. From some posts there have been warnings about the use of this damaging the foliage, but it is what I have been using. Use the most diluted rates suggested on the label e.g 15 or 20 millilitres per
3Litres. The good thing about this is it is a systemic insecticide, so the insect will die both upon contact and also when it chews the leaf. In my case it suits me because I’m not also at that same garden.
Other solutions are pyrethrum based insecticides derived from natural chemicals, in this case many insects don’t like plants from the daisy family which include chrysanthemums, and marigolds. At high concentrations as they are made, they are quite effective. They will only kill on contact (not chewing) so you have to spray more frequently. Neem Oil is another natural alternative that has been mentioned that has been known to kill them.
In this case spray every 2 weeks, especially when there is new growth. If there is no new growth, spray and thoroughly wet inside the unopened crown of the plant to insure that the next flush of growth get a good start and to kill any larvae hiding there, burrowing into the top of the plant.
2 extremely natural ways that have been mentioned to kill them are vinegar and water mixture, or something I use in the garden is a commercial natural product if you can find it is a garlic-capsicum spray mixture that seems quite effective. It smells bad and don’t get the stuff in your eyes
Otherwise important, is to try to increase the health of the plant. Give it a liquid feed and good watering in dry times to try to produce a new flush of growth.
Here are some other links to check out for this curse: