Two females probe the limb of a sugar maple looking for larvae of the pigeon horntail wasp, into which to lay their eggs. I think these wasps are extremely impressive and though I don't see them often, when I do, it is a treat! Including their ovipositor, these females can measure in at up to 110mm; without counting the ovipositor, they are still a good size, up to 75mm, considerably larger than the not often seen males (measuring perhaps up to 35 or 36mm). To see the male: http://www.pbase.com/laroseforest/image/156896668