Wednesday, July 17, 2013

The Wasp Version of Baby Bottles

Well, I'm the first to admit that caring for a child is difficult, especially during infancy, but if you think hauling around a diaper bag, stroller, and baby bottles is bad, just be glad you aren't a wasp mother, working to provide food for her growing youngster(s)!

I lucked out yesterday and captured this sequence of a female wasp pulling a spider she had caught, then paralyzed with her sting.  She is taking the spider back to her nest - it's baby food, wasp style.

Note that the wasp is roughly an inch long.  To my eye, the spider is as big as she is.  Although these photos are rather colorless and filled with lots of empty space, I wanted to give you a sense of how far she was dragging her burden.  (Realize, too, that I missed the first 10' or so, across the flat surface of the breezeway, as I ran inside to get the camera.)

At this point, Mama Wasp is dragging the spider back to her nest, where she will add it to another spider or two or three, then lay an egg on them and close up the cell.  The spider isn't dead, just paralyzed, so it and the others will stay there in the cell, perfectly "fresh" despite hot summer temperatures, until the egg hatches and the young wasp larva starts eating.  Each cell in the nest is provisioned with just enough spiders to rear one young wasp.

As Mama Wasp got to the edge of the breezeway, she dropped her catch to go ahead and scout the drop-off out.

Coming back, she picked up the spider and drew it to the edge. 

It went over the edge easily, but she lost her grasp on it and seemed to temporarily lose it, evidently not noting where it landed.  (It was caught in a gap between the top wooden step and the side of the breezeway.)

For several minutes, Mama Wasp wandered around - up onto the flat surface of the breezeway, down the side of the concrete,...

...onto the mulch down below, back up and around, onto the step, until finally she figured out where the spider was and grasped it again.

At one point, she and the spider fell off the edge of the wooden step into the space below the steps.  It didn't seem to faze her.  Mama Wasp just gathered the spider up more firmly and tried to figure a way out.  She didn't end up finding the shortest or easiest way, but she did work her way out.

Now she had a vertical to climb, carrying her bounty with her.  She worked her way across the surface....

...until she came to a place where she could get a better footing.

Up she and the spider went...

...over the little ledge, and into the crevice where her nest was evidently waiting.


A few final tugs, and Mama Wasp and her baby food were hidden from view.

Ever since we've lived in this house (6 years now), we've noticed wasps flying around these steps to the back yard during the summer.  They've never been aggressive and we've never really figured out where they were coming from.  We've pulled the wooden steps away, but seen no sign of any wasp nests.  I've looked in the mulch, searching for ground entrances.  No holes anywhere.  The answer was solved yesterday by Mama Wasp - the nests are between the two layers of concrete forming the foundation and the breezeway surface.  I am guessing that the wasps we see flying around the area are males, waiting to fertilize the females as they emerge from their crevice.

Looking at bugguide.net, I am pretty sure that these wasps are spider wasps of the genus TachypompilusThe information on this genus states that they are primarily found in open country (we qualify) and that they are often found nesting around (old) building foundations or in rock piles.  Again, the habitat fits quite well.

These are "solitary" wasps, like mud daubers.  The males have no stingers (which are modified egg-layers), so they can't sting.  The females are too busy making nests, provisioning them, and laying eggs to bother with stinging.  Typical of solitary bees and wasps, you seriously have to pick up a female or make her fear for her life to get her to sting you.  She just wants to avoid any situation where her likelihood of dying increases, because as soon as she dies, her chances of reproducing are gone.

As a last comment, I found it interesting how Mama Wasp carried her paralyzed spider up the foundation wall:  she backed up the entire way, and she appeared to be dragging it by holding on to one of its pedipalps (longish, arm-like mouth parts that spiders have in addition to their 8 legs).

It never ceases to amaze me how much I can still learn around my garden, when I keep  my eyes open and my camera ready.  The internet is an incredible resource as well - how ever did we manage to learn new information back in the days when every identification depended upon a preserved specimen and a visit to the local library, at the very least?!

Sometimes even I, the Luddite at heart, can appreciate modern technology!

4 comments:

Marilyn Kircus said...

WOW! What a wonderful post. I'll add you to my blog list and go back and read previous blogs. I love finding out about the hidden lives of small creatures, but seldom have the patience to watch long enough or even have the attention to detail that would allow me to notice such in the first place.

Thanks so much for taking the time to share this with us.

Gaia Gardener: said...

Thank you, Marilyn. Glad you enjoyed it!

Gardener on Sherlock Street said...

What a great post. I learned a lot. Amazing how this all works. We all need to take more time and watch what is happening around us.

Janet QueenofSeaford said...

I love watching insects, what a great find to document.