David Hare-Scott wrote:

I have eggplant borer (Leucinodes orbonalis) in my eggplants for the
third year running. I have tried spraying regularly with pyrethrum
this year which has reduced the rate of infestation but not eliminated
it. Without spraying I get about 10% edible fruit, with spraying
about 50%. I have searched the internet and it seems there is no cut
and dried solution. One of the problems is that the eggs are layed by
moths continuously through the growing season and the grubs are only
vulnerable for a short time to contact toxins before they burrow into
the fruit and vanish. I prefer not to use systemic insecticides and
it isn't clear that they are completely effective either. I don't
need 100% effectiveness but only 50% is too much waste for my liking.

My next method of control (next year) is to grow my eggplants in net
cages to keep the moths off them. Before I go to this trouble does
anybody have experience of the problem who can offer a practical
solution that is better than 50%.

Maybe exclusion bags. You can buy exclusion bags, or maybe use paper bags
(or make some bags from nylon fabric).

e.g. http://www.greenharvest.com.au/pestc...sion_prod.html

Do the plants continue to flower while other fruit are growing? If so, you
will presumably need bees to fertilise the flowers. Exclusion bags would
allow this - net cages wouldn't.