As the tomato fruit develops into full size it becomes very attractive to a variety of grubs and caterpillars. The moth knows the fruit will soon ripen providing a storehouse of food for the new and developing (grubs) insects.
Even though the fruit is still green, the moth finds the tomato flesh attractive and a perfect hatching location for the next generation of caterpillars. At this stage the hole of the immature caterpillar is very small and hard to detect. Larger grubs leave larger holes. Once mature the grubs leaves the fruit, ruined for human consumption, and dig into the soil to pupate into moths. If it is dry the grub will hibernate for up to six months but with rainfall or watering the moth is encouraged to develop.
Keeping the plants well fed with seaweed tonics and organic solutions helps build resistance and strength in the plant and the fruits. Regular fertilising and even watering maintains vigour and reduces the possibility of disease such as blossom end rot. This all encourages healthy growth and fruit production.
Can we live with it? No, Grubs consume fruit and destroy harvests.
Control: It is important to stop the caterpillar from entering the fruit as it is impossible to stop with insecticides once entry is gained. Fruit exclusion bags can be purchased mail order from Green Harverst (www.greenharvest.com.au) and are mesh bags that go over the fruit, allowing the fruit to develop safely inside the bag. These mesh bags come in many sizes and can be used again.
Organic: Keep well fed with seaweed tonics and spray with Success, an organic product containing 'Naturalyte'. There are several predators of this pest but they are slow to become activated. Some gardeners have tried the new agricultural oils with some positive response. PestOil and Neem oil, being the most popular.
Chemical: Tomato dusts can also be effective as they contain both an insecticide and a fungicide but the withholding period must be strictly observed.