I know, I am posting 2 individuals in the same photo. I apologize. But I want to ask a question and tell the little story.

On July 23, 2012 I was searching for aphids on goldenrod, Solidago sp. I didn't find any aphids but found other insects so collected a few. These 2 ripiphorids were dead, each in a spider's web. I stole them. (I really like these beetles.)

My question: Can anyone tell me about the size difference?

One of the other insects I collected was a leaf beetle
on which (a few days later, under the scope) I noticed a triungulin.

On July 31, 2012 I was again searching the goldenrod in the same vicinity. Again I found 2 dead ripiphorids in spider's webs. Again I stole them. Again they varied in size by .5mm.

As I continued looking, to my delight, I saw several live ripiphorids on and around the goldenrod. All told I had now seen more ripiphorids in these 2 days at this location than I had seen in my whole previous life (ok, that's not saying much)

I also collected 2 leaf beetles and a bee for the triungulin (on the previous leaf beetle) and a bit of the goldenrod. Later that day there were 10 triungulins. Perhaps they had been on the goldenrod? By evening one larva was on the ventral side of the leaf beetle and another larva was on the leg of the bee
and the rest were running around on the goldenrod.