I'm in Tucson also, and I keep getting those nasty green tobacco hornworms on my sweet olive bush. Not exactly an infestation, but 2 or 3 will leave their mark, and quickly -- they're ravenous and they get HUGE! They eventually turn into some kind of sphynx moth (except the ones in my yard, hehe) The only other "new" caterpillar problem are the Genista caterpillars attacking my Spanish broom. Spanish broom is mostly green twigs with a few tiny leaves (similar to a Palo Verde or Ephedra) but once the leaves are gone, they simply devour the outer wall of the stem, causing the stem to die. BT spray kills them within a day, but I'm having to apply it weekly just to keep up with the population explosion. The creature I'm really having problems with this year are Black Widows -- they're everywhere! I go 'hunting' every few nights and kill at least a dozen every time. I can't stand their filthy, garbage-collecting webs, UGH!!!!!

Thanks you for the response, Sherry. It's good to know that the painted ladies will be okay. I wasn't sure how they would interact. Unfortunately, I don't think we have any of those plants, not even wild tulip trees. My parents had to buy ours, which is why they don't want the tiger caterpillars munching on it and perhaps damaging it. I've been trying to give the tigers willow leaves and branches, and while they seem to like climbing on them, I haven't noticed them eating any. They're sticking to the tulip tree leaf. Isn't there anything else? If there isn't, my mom will probably let us put them back, but I'm hoping for an alternative.

Army worms and tent caterpillars are different. The ones here in Alberta are generally Forest Tent Caterpillars and have a blue stripe on either side of their body and white spots down their back. Eastern Tent Caterpillars have a white stripe down their back with a row of blue spots on both sides. They are related and both are often called Army worms. There are others considered army worms as well and are colored differently, although, they usually prefer grass crops as compared to tent caterpillars who prefer leaves of trees and other deciduous plants. IMO, all of them are just awful to deal with but the birds like them......as did I when I was a caterpillar collecting kid! :) As for control.....maybe a soapy solution like Safers, sprayed on the plants will help. :) Ginny

I only have a white lilac and not sure if the bloom time is the same as the purple, but mine bloomed as usual this year, despite the weather. I would think that if your shrub has some kind of disease it would show up on the foliage, no? You might want to prune off any dead or dying blooms as soon as you get a dry morning and hope for a better spring next year.