From Sci-News: (hat tip via Dave at ESCONI Yahoo Group)

This piece of amber preserved the event in remarkable detail, an
action that took place some 100 million years ago in the Hukawng Valley
of Myanmar.

The fossil also contains the body of a male spider in the same web.
This provides the oldest evidence of social behavior in spiders, which
still exists in some species but is fairly rare. Most spiders have
solitary, often cannibalistic lives, and males will not hesitate to
attack immature species in the same web.

“This juvenile spider was going to make a meal out of a tiny
parasitic wasp, but never quite got to it,” said Prof George Poinar Jr.
of the Oregon State University and world expert on insects trapped in
amber, who co-authored a paper in the Historical Biology: An International Journal of Paleobiology.