lilipili wrote:
Late last summer my friend and I started harvesting our eggplants,
capsicums and the last of the tomatoes (we're in Melbourne). At the
end of the season we found lots of tiny holes in the vegies. When we
cut open the fruits, there were medium sized white bugs - lavae of
some sort - a lot bigger than the tiny hole made by the bug. It's a
bit of a shock to find this squirming sometimes quite large grub like
bug. We've just put in more summer seeds and want to know what the
bugs are and how to deter them for this coming spring/summer season.
Does anyone know what they are?



There are a number of insects that fit this description. There is the
eggplant borer and various types of tomato "worms", they aren't worms but
insect larvae. Since the three fruits are fairly closely related there may
be some bugs that inhabit two or all three - I am not an entomologist.

Having had the eggplant borer I found that the typical way they work is for
a moth to lay eggs on the plant on or near the flower or budding fruit. The
eggs hatch and the larvae burrow in, this gives them food and shelter at the
same time. The black substance in the burrow is of course bug crap.
Eventually the larva transforms to an adult that flies off to do it all
again. This habit of burrowing makes it hard to kill the larva with sprays
as it requires frequent spraying to get them before they get deep inside. I
am not sure if a systemic spray, as opposed to a contact insecticide, would
get them inside the fruit but such are rather toxic and I don't want to use
them.

A potentially safer and more effective method of control is to exclude the
moths by bagging the fruit or caging the whole plant in mesh. This is going
to be a problem if you need the fruit to be insect pollinated. This method
of control is complicated by the fact that the plants flower and set fruit
progressively not all at once.

This site: http://www.beeculture.com/content/pollination_handbook/

will tell you about insect pollination and the effect of non-pollination on
fruit development. In brief, insect pollinators are important for eggplant
and capsicum but not tomatoes. So cage your tomatoes and see if that fixes
the bugs.

Last year I tried spraying the eggplants a few times and this did improve
the yield but it was not 100%. This summer I am going to try a combined
strategy on eggplants. I will spray the individual flowers religiously with
pyrethrum (which is not very toxic) until the petals fall. I will then bag
the fruit. Since each plant only has a dozen or so fruit this ought not to
be too tedious. I wouldn't do this with tomatoes.

David