Think about it... a wasp larva hidden inside this small gall has caused the oak tree to grow the gall to feed and shelter the larva. Not only that, but the gall-maker also causes the gall to ooze honeydew which attracts yellowjackets and ants. These in turn, protect the gall as a food source, and in doing so, are unwittingly protecting the gall's inhabitant from parasitic insects.
Now, it is amazing how the Cynipid gall wasp larva causes its host plant to grow a structure that houses it and also feeds it,
but, hey, gall-makers do that kind of stuff all the time.
What this larva is programed to do is bordering on awesome.... the wasp larva can cause its host oak tree to turn the larva's larder/shelter into something like the nectary of a flower whose job is attracting guards (protectors) instead of pollinators. Profound!
Check out the photo below and you'll see what I mean. Who would argue with this guy... when you can see it claims the gall... and says, "It's mine.. all mine... and if you stick that big thing any closer... I'll..."
ants milking honeydew from aphids, a finger placed nearby will soon be covered with agitated, biting ants.
Pin Oak's lower branches characteristically droop, so as I walked past, these amazing galls were right at eye level and easy to observe. Finding information on the galls wasn't quite as easy. I found little written about these acorn galls.
Ahhh, if only honeydew galls were really big (I'm thinking big enough for a good human-sized sip of honeydew) and there were always lots of them! Well, a moderate amount of them... we need acorns as well.
Maybe I just wish... that there would always be some pip galls in the pin oak.
BTW... I doubt many people purposefully search the web for acorn pip galls. Perhaps you, my regular readers, would pass this post along (via email, etc) to some folks you know who would enjoy these pictures of yellowjacket-protected pip galls. Wouldn't it be great to perpetrate some online pandemonium over pip galls in the pin oak?