Doreen stated "Great job obtaining info Ian. Thanks. Now where can I
get those flys."
Unfortunately, without a review of the literature and some work on
potential parasites, it would not be possible to identify suitable
tachnid fly or hymenopterous wasp species that would be useful parasitic
control for the iris borer. The information might already be in the
literature somewhere but it would have to be found and tested in the
laboratory ove a summer. There would be no difficulty getting borer
larvae but one would also have to breed some of the flies or wasps and
see whether they did lay their eggs in the larvae of the borers.
Furthermore, one would have to take the test a step further because they
might attack the borer larvae directly but they would also have to be
able to reach the larvae in the plants, which could be a difficulty.
Normally, in hymenopterous insects, this is achieved by having a very
long "sting" which is used to penetrate the plant and find the larvae
and then the egg is passed down the "sting" and injected into the
larvae. The best examples are wood wasps that fly around in summer with
a "sting" (ovipositor) which is as long or longer than the insect
itself. Tachnid flies usually dig down into the soil themselves to find
All this is to explain why we could do tests next summer but probably
not find a control animal on the market right now. A well designed test
plan could, however, be run in a large number of gardens around the
country with the help of members of the list.
We need AIS to fund a start on this important problem to most irisians.
Ian in Ottawa