Plant Doctor Archive

Green beetle

THIS last season my tomatoes were plagued by a green beetle that appeared to suck the outside of the fruit, where they got hard patches and areas of rot. How can I get rid of them next season? And can you recommend anything for white butterfly caterpillars? I use Derris Dust but it doesn't seem to give me good control.

IT sounds like your tomato problem is caused by green vegetable bugs which, while damaging fruit, also feed on stems and leaves of a variety of plants. They are susceptible to most insecticides, including the low-toxicity types such as Garlic & Pyrethrum and Nature's Way Pyrethrum, though you need to make sure the spray makes contact with the bugs.

Ideally, check your plants regularly and try to control the bugs in their young stage before they can cause much damage. Young green vegetable bugs don't have wings like their parents - they are smaller and come in a variety of colours often with black and white, or brownish markings. Derris Dust should also give good control but, as with white butterfly caterpillars, you need to make sure to apply it where the bugs will make contact, often underneath the leaves. And you must apply it frequently (7-10 day intervals) and more often in wet weather as rain can reduce its efficacy.

The sprays mentioned above should also knock down your caterpillars but you could also try Success Naturalyte, an environmentally friendly product which affects caterpillars only.

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