[Jacqui]

As you know Dr Phil Lester has been investigating Ophryocystis elektroscirrha in monarch butterflies in NZ.

I have been giving this a lot of thought…

I first discovered Oe in monarchs in my garden 15? 20? years ago and at that time no-one in NZ knew it existed. Of course, it’s probably always been here, as long as the monarchs have but the major change has been the proliferation of social wasps over recent years (50 or so). As you know, the social wasps eat our caterpillars.

Now, if you live in a warmer area you will have noticed that the swan plant is no longer an annual but will last for several years. When I was younger (50 years ago) we would need to buy swan plants all season for food – not so now, because the swan plants grow to 2-3 metres tall in this part of NZ (Auckland, also Bay of Plenty and Northland).

Over the last two years, however, I’ve noticed while I apparently have some beautiful swan plants in my garden, female monarchs appear to be laying on most of them but mostly aren’t leaving eggs behind.

Could this be because the swan plants have a residue of Oe, and that the monarchs sense this?

For this reason, I’ve removed about 40 mature swan plants and left 5-6. I am sure that there will be many seedlings sprouting when the weather gets warmer. I also intend to try spraying the plants that are left with a bleach solution (10% bleach/ 90% water?) and will leave that on the plants (30 minutes?) before rinsing it off. 
I will be sterilising all of my caterpillar castles.

I also plan to catch a few of the earliest butterflies and put them in my butterfly house with some healthy plants for egg collection, and will sterilise the eggs.
Hopefully this will reduce the incidence of Oe in my neck of the woods.

What are your thoughts?

[GraceGriffin]

Yes, I’ve been using the milk and warm water but unfortunately find it ineffective.

[Jacqui]

Hello Monkey and Grace – have you looked around the posts about aphids? Use the hot tags to the right. Also, you might like to start a post asking your questions and seeing what others have to suggest. Some very helpful tips have come up here in the past.

[GraceGriffin]

The worst affected plant with aphids is a new plant this year, also the plant which has the greatest number of caterpillars hatched.

[monkey]

Another thing with old plants, they seem to be the ones worst affected by the yellow aphids, & subsequent sooty mould. Could it be that the aphids lay eggs & these over winter on the old plants?

[Jacqui]

Hello Grace

I didn’t know that my plants were affected by 0e and I will never know but I put my plan into action. The two plants that I kept I sprayed before spring.

I purchased new plants and also a lot worse self soon.

I have had very few diseased caterpillars or pupae this season so sounds like my plan might have worked

[GraceGriffin]

How do you know plants have OE and what season do you spray

[LeslieD]

good thinking and advice!. i’ve got a lot of large old plants and i noticed butterflies not laying on them last year too. They preferred younger plants. My plants typically last a couple of seasons and I’ve always got some on the grow. I use miltons to disinfect my castles regularly and any plant i suspect of having had a sick caterpillar but i think I’ll get out and blast everything this year .. in a couple of months though :0

[Author]

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