Plant Doctor Archive

Beetles and bugs

WE have had a lot of trouble this year with the green hard back beetle and mealy bug, which I understand turns into what we call penny moths. When spraying with Target, does it kill these insects or does it simply force them to move somewhere else?

THE beetle you refer to is probably green vegetable bug and the "mealy bug" sounds like the nymphs (young) of the passion vine hopper. Both these insects can feed on a wide range of plants. In many cases, infested plants show little signs of damage, even with quite high populations of the pests, but some vegetables and passion fruit vines in particular can suffer quite badly.

If your Target spray actually hits the bugs before they fly or leap away, there's a high likelihood they will die. Target also has what is described as "translaminar activity", which means it travels through the leaf and probably also into the stems. So for several days after spraying, any insect that feeds on the plant will also be affected by the spray. This is why, with edible plants, it is very important to check the withholding period stated on the Target container label, to ensure you don't harvest and eat anything that might still contain traces of spray.

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