nhbabs, I agree mine has to be smaller. I wonder if it's 'Texas Scarlet,' but only assuming it is a "newer" variety as it would have been planted about 10 years ago. The previous owner could have gotten it from old stock, who knows. But, I'm sure it's small, too. Does your smaller one have thorns? Internet searches all say they should have thorns, too. Diggerdee, I'm almost in zone 4, and many people around here plant for zone 4. We're probably much much later than you! My forsythia just finished blooming and the creeping phlox has just finished peak. Still spring blooming here! I pruned the quince quite a bit today. Cut out many dead canes, cut back existing canes. The workers should already have been here, but I'm glad they're late as it gives me time to prepare. Now to figure out where to put it, especially if it can get big! I'm hoping pruning will help it transition better as it will have less plant to try to maintain.

Sounds like a disease. Suggest you ask same question at Butterfly Forum.http://forums.gardenweb.com/forums/butterfly

Your hostplant choice could be the problem. Just because a caterpillar eats something does not mean it can complete its life cycle on it. I raise polyphemus moths. I have seen box elder maple listed as a hostplant for polyphemus. Some years ago now, I tried repeatedly to raise polyphemus caterpillars on box elder maple since I have a lot of those trees. The caterpillars would live up to 5 months on it, much longer than the approx. 6 weeks they would live on a hostplant that supported normal development. And they would all eventually die. One year I tried to raise cecropia moth caterpillars on a non-native viburnum my neighbor has. Caterpillars ate it but they never developed past 4th instar and eventually died when the weather got cold.

I agree with floral that the plant in question is unlikely to be a lilac. There is no lilac species or hybrid that holds its blooms all summer. Most will bloom early in the season for a couple of weeks at most. Even the so-called reblooming forms (like Bloomerang) are very intermittent in their flowering and the flowers on all types will dry and brown in a matter of a few weeks. Also, the largest individual lilac flowers are far less than a half inch across - nowhere near the size of a nickel - and 7' is pretty short for a common or standard lilac. 12-15 feet is far more typical.