These caterpillars had already devoured half the leaves on my young crabapples when I finally discovered them.  How could they be missed?  Fat, spotted and making no attempt at disguise, they were busily on their way to butterflies.  It’s interesting that they don’t eat the leaf veins, as you can see the skeleton on the left.  Why bite into tough veins when surrounded by succulent foliage?  I picked them off and sprayed some neem oil to keep anyone else away.  I’ll have to keep my eyes open…..