Plant Doctor Archive

Aphids on swan plant

I HAVE a swan plant that is laden with beautiful monarch caterpillars. However, it is also covered with aphids. They are bright orange and are on everything. I certainly don't want to use a spray that will harm the caterpillers, but the aphids are taking over and the poor plant looks a little sad. Do you have any handy hints?

IT sounds like you have a nice healthy colony of oleander aphids. I wouldn't worry about it too much as the monarch caterpillars will do much more damage to the plant than the aphids, yet the plant will probably still survive. A reasonably large swan plant can usually put up with having its foliage completely stripped off by monarch caterpillars. Once the larvae stop feeding and pupate, the swan plant will most likely produce more leaves and start growing away again, despite the aphids.

Any of the sprays you can get from garden centres to dispose of the aphids would have a detrimental effect on the caterpillars, so perhaps the best and easiest way to knock the population back is to rub them off by hand. Wear gloves if you don't want aphid juice all over your fingers. Once the monarchs have gone you could spray for the aphids, if you feel the need.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.