A little fun: birds and grass carrying wasps

I’ve been enjoying our back porch this summer, sitting under our shady honey locust drinking coffee, or relaxing, or reading, or eating. I especially enjoy the hammock my family gave me for my birthday this spring – why did it take me so long to get a hammock??  

While I’m outside, I watch and listen to the world around me.  I’ve put up a number of different bird feeders, and I watch to see who comes.  For a while, nothing but catbirds visited our yard.  They can sing so sweetly, but mostly just call in their harsh ‘MEOW’ sounds that once had me convinced, long ago, that a poor kitten was stuck in the bushes outside our house.  Even though my dad told me it was just a bird calling, I hunted for that kitten for at least an hour.  Only this year did I notice that the feathers under a catbird’s tail (their ‘rump’) are a dusty orange color (my kids and I have started calling them ‘orange butt birds’). We’ve seen many goldfinches, chickadees, titmice, song sparrows, downy woodpeckers, cardinals, blue jays, and the occasional nuthatch.  Earlier in the spring we saw Carolina wrens, and for a single day each, rose breasted grosbeaks and yellow-rumped warblers, all three of which I had to look up to identify.  I put up a hummingbird feeder, and every time a hummingbird visits, my brain goes through the same slow process of “…what is that? Is it a huge bug? A dragonfly? something worse, like a flying cockroach? No…but what is it??  Ohhhhh a hummingbird!”  Every single time.  I guess hummingbirds just don’t fit into the ‘identifying features of birds’ category my brain has constructed over the years.

Catbird (a.k.a “orange butt bird”)

By far the most common visitors to our porch are wasps.  I’ve been stung a handful of times in my life by bees, wasps, hornets and yellowjackets, and so I have a healthy aversion to large, buzzing insects with jet black and bright yellow colors.  But sitting on the porch is so relaxing, especially in the hammock. Instead of moving away from the wasps that visit our porch, I watch them.  While some aggressive ones build nests in our outdoor light fixtures, which we spray and remove, others seem more … gentle?  One type of wasp in particular is obsessed with our patio furniture.  These wasps are drawn to the holes drilled into the metal of the furniture to let rainwater drain out.  They fly around these small holes, alone, land and explore them inside and out. They fly away, only to return carrying long streamers of grass or small puffballs of some kind of fiber, which they stuff into the holes, fussing over the exact placement of each piece. 

These wasps are so focused on their task that I can watch as one flies right up to a drainage hole in the chair I’m sitting on and, just inches from my leg. If I don’t inadvertently put my hand or leg on top of it, the wasp will completely ignore me.  I find them almost…cute?  Can I use ‘cute’ to describe a wasp? I find their behavior so intriguing, so different from my idea of what wasps are like, that I looked them up on Google.  I entered “wasp that carries strings” as my search term, not expecting much, and was surprised when “grass-carrying wasps” was at the top of the list of results. Huh!  I learned that these wasps are sphecid wasps (Family Sphecidae) which are more closely related to bees and ants than to vespid wasps such as yellowjackets and hornets (Family Vespidae).  While vespid wasp species are mostly eusocial (colony-building), and will vigorously defend their communal nest, sphecid wasps are solitary.  A single female will build a nest in the ground (digger wasps and cicada killers), in elevated holes or crevices (grass-carrying wasps), or out of mud attached to surfaces (mud-dauber wasps).   

Wasps, bees and ants have an interesting sex-determination system, “haplo-diploidy”, which means that fertilized eggs (which are diploid) become female offspring, while unfertilized eggs (which are haploid) become male offspring.  An adult female will mate with a male and then store the sperm until she is ready to lay eggs.  Only female wasps (or bees, or ants) can sting because the stinger is a modified ovipositor, an appendage found on female insects which is used in egg-laying. As a female deposits eggs, using her ovipositor, she can open or close access to the stored sperm, allowing some eggs to be fertilized and others, not.  In Isondontia mexicana, the species of grass-carrying wasp probably visiting my porch, the female lays generally between 3-5 eggs, and the first eggs laid, farthest from the nest opening, are more likely to be fertilized (female) than those closer to the opening, which remain unfertilized (male).

Sphecid wasps are predatory and will, after laying just a few eggs in the nest, provide crickets, katydids, or other insects for the larvae to feed on after they hatch. After feeding on the insects provided by their mother, the larvae will spin cocoons, and then metamorphose into adult wasps. Oddly for a species that is labeled a predator, the adults can’t feed on the prey they catch. When the larvae metamorphose into the adult form, their mouthparts change, converting from biting, chewing structures into sipping structures.  Adult wasps, like butterflies, can only sip nectar through a proboscis.  Because the adult wasps feed on nectar, they act as pollinators for a number of plant species, preferring those with white flowers.

In that brief moment before I fully process what my eyes are and ears reporting, the appearance of a hummingbird leaves me instantly ready to run or avoid a flying threat.  Once my conscious mind catches up, I see them for what they are, tiny miraculous birds. With grass-carrying wasps, that shift in perception from fear to wonder is less straightforward.  They are still wasps, with the same overall body design and ability to sting as their more aggressive relatives.  But after a summer of watching them work, I now let them fly around me as I sit, quietly enjoying my back porch, and I watch with the same sense of wonder I feel when I watch a hummingbird.

Sources and further reading:

Catbird image: https://commons.wikimedia.org/wiki/File:Gray_Catbird_-27_100-_(34121108540).jpg

Grass-carrying wasp video: my own!  (in the background you can hear my 7 year old strumming a guitar)

Johnson, Brian R., Borowiec, Marek L., Chiu, Joanna C., Lee, Ernest K., Atallah, Joel, Ward, Philip S. “Phylogenomics Resolves Evolutionary Relationships among Ants, Bees, and Wasps.” Current Biology, vol. 23, no. 20, 2013. pp 2058-2062 2013. https://doi.org/10.1016/j.cub.2013.08.050

O’Neill, Kevin M., O’Neill, Ruth P. “Sex Allocation, Nests, and Prey in the Grass-Carrying Wasp Isodontia Mexicana (Saussure) (Hymenoptera: Sphecidae).” Journal of the Kansas Entomological Society, vol. 76, no. 3, 2003, pp. 447–454. https://www.jstor.org/stable/25086133

O’Neill, Kevin M., O’Neill, James F. “Prey, Nest Associates, and Sex Ratios of Isodontia mexicana (Saussure) (Hymenoptera: Sphecidae) from Two Sites in New York State,” Entomologica Americana, vol. 115 no.1, 2009, pp. 90-94. https://doi.org/10.1664/07-RA-009.1

http://bugoftheweek.squarespace.com/blog/2013/11/11/window-wasps-the-grass-carrying-wasps-iisodontiai-spp

https://ento.psu.edu/extension/factsheets/grass-carrying-wasp

https://www.canr.msu.edu/news/the_grass_carrying_wasp_a_solitary_wasp_that_builds_nests_in_unusual_places

https://www.everythingabout.net/articles/biology/animals/arthropods/insects/wasps/sphecid_wasp/

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