I've never had this problem last year, nor the year before. My yard is infested with tropical milkweed, which I consider a good thing. Not only do I get lots of other necter visitors, but the monarchs use it as a year-round breeding ground. Strangely, this year I've only had THREE known caterpillars that pupated and eclosed successfully. I've observed hundreds of eggs, but it seems that the newly hatched ones just disapear. I haven't seen a cat larger than an inch for months. So if there's any butterfly experts around, why am I having such a high death rate/why am I seeing so many eggs but very little to NONE caterpillars!?