It is important to remember that whatever pest/parasite affects your caterpillars, this is the way that Nature intended it to be. Nature and biodiversity are meant to be diverse. All creatures depend on other species (plant and animal) for their survival. No one species or animal should be considered as ‘good’ or ‘bad’. Everything is part of the food chain, i.e. it eats others (animal and vegetable), and is consumed by others.A central principle of ecology (the study of ecosystems, ecosystems being the natural unit in which a species lives) is that each living thing has an ongoing and continual relationship with every other thing that makes up its environment.
However, if you want a garden full of butterflies, then it is important to discourage the other creatures that feed off it. You can exterminate them, discourage them, or move them to other parts of the garden. Considering a Monarch butterfly can lay around 1,000 eggs – even the norm of 200-300 – if every one of these eggs resulted in a healthy adult, we would soon be overrun with Monarch butterflies. So do not despair!
We hope that the following handouts are helpful to you. Having a garden that “suits” butterflies is the best way of encouraging them. See the separate page on ‘butterfly gardening’ for ideas, and to get a list of typical nectar plants, download the colourful poster.
There are ideas on the two attachments below for removing the major species that affect your milkweed (e.g. swan plant) and the major predator of caterpillars – the social wasps.
Please consider joining the Moths and Butterflies of New Zealand Trust so that we can put together more of this information.
Some great photos of aphids/ladybirds interacting here.