Saved by the camera

I was standing near the crabapple tree when a dark shape on one of the leaves caught my eye.  As I moved closer, I saw that there were actually two dark shapes -- a parasitoid wasp and a jumping spider. 

A jumping spider sneaking up on an ichneumon wasp.

The jumping spider was stalking the parasitoid wasp, which was preoccupied with laying an egg.  With the spider poised to strike, I thought the wasp had no chance to escape.

The jumping spider closes in on the ovipositing parasitoid wasp.

Mysteriously, though, this was as close as the spider got.  After looking at the wasp for a couple of seconds, the spider abruptly turned and moved back down the leaf.  Perhaps it was spooked by the camera, or perhaps the wasp was simply too large for the spider.  Meanwhile, the wasp continued laying its egg.  A couple of minutes later, it turned to face the site where it had been laying an egg or eggs, then spent some time apparently chewing.

The ichneumon wasp chewing nearby its oviposition site.

Once the wasp had flown off, I turned the leaf over to see what had been parasitized.  What I found was the mine of a tentiform leaf miner, with a hole where the wasp had been facing.

A tentiform leaf miner mine with a hole (on the left) where the wasp appeared to be chewing.