This is the first year I've tried growing hardy hibiscus from seed. I've
got some plants in the ground and some in pots. Unfortunately the
caterpillars are devastating them. I'll go out and find entire plants with
their leaves "skeletonized." I'm not sure exactly what kind of caterpillar
is doing this. It resembles a hornworm in color/shape, but I haven't seen
any really large ones to know for sure. (The largest I've seen on plants is
about .75" long and about 1mm in diameter.

In the past when I've had problems with these kinds of bugs, I've sprayed
BT. I started doing that this season. Unfortunately, we've had almost
daily hard rains that I'm guessing makes it hard for the treatment to stay
on the plant. I've sprayed repeatedly with BT and the plants keep getting
eaten and live worms are still on the plants. At one point I thought my BT
had gone bad since it was from last season. I bought now BT and still the
problem persists.

Can anyone offer any recommendations? So far the bugs only seem to be going
for the hardy hibiscus (and possibly a nearby mexican petunia, but I'm not
for sure on it).

These plants have been sprayed at least 6 times with BT since late May. I
think I need to move on to something else.

Tony