I found a bunch of these on my cherry tree (a self-pollinating Lapins cherry) last week:
The larger black spiky things with orange middles are lady beetle larvae, which can eat hundreds of aphids before they become adults. The vast majority of other little round bugs are aphids, of course, and aphid carcasses. I’m not sure what the silver bugs are (about twice as long as the aphids, close to the main stem of the leaf).
© 2007 Scott Wiersdorf