Tay Meadows Tidbit – Great Black Wasp

Great Black Wasp

Apparently Nature felt that I hadn’t been out to visit enough recently, and decided to come to me. I’d just gone into the washroom to return the tea I’d rented (as my dad likes to say) and was startled to discover a GIANT BLACK INSECT squirming at the water’s surface. It was big, at least an inch and a half (35mm) long. And, it turned out, it was a wasp. Big + wasp don’t usually go hand-in-hand as a favourable combination to me (although, I did profile some gentle giants last year; this one was close to the size of those, though not so robust), so I was a little intimidated. I scooped it up in a container and took it outside where I took some photos while it dried out, then let it fly away.

Appropriately, the insect is called a Great Black Wasp (Sphex pensylvanicus). BugGuide lists their average size as 25mm (1″), but this individual was definitely larger than that. BugGuide also remarks that males are smaller than females, so given the size I would suspect this to be a female.

Another clue might be the large mandibles you can see below her face. Great Black Wasps also go by the name “Katydid Hunter” or “Steel-blue Cricket Hunter”. The females capture katydids and crickets – sometimes as large or larger than they are – paralyze them with a sting, and carry them off to their burrow nests. There they lay an egg on the still-living katydid. When the larva hatches, it feeds on the katydid. Paralyzing the prey, rather than killing it outright, prevents the prey item from becoming dessicated or decomposing before the egg hatches. The young overwinter in the burrow; adults emerge and are present in July through September. Interestingly, while the adult catches katydids to feed the young, it itself actually feeds on nectar from flowers. I don’t know what this one was doing inside – there are neither katydids nor flowers in the house, not even dirt that it could burrow in.

Some interesting studies have been done with digger wasps of the genus Sphex. When females return to their burrow with their prey item, they drop the katydid at the nest entrance and go inside just to make sure the coast is clear before they drag the cumbersome object in. If they went in with their mouth full they could be caught in a compromising position that might make it difficult to defend themselves. If a researcher moves the katydid a few inches from where the female dropped it, when she returns outside she has to search for it again. She can find it, but then upon returning to the nest must drop it and inspect the burrow again – her genetic programming forces her to go through this behavioural sequence each and every time, no matter how many times the researcher moves the katydid. Some have cited this as an example arguing against the idea of free will, but I suspect the genetic programming in most insects is probably much simpler than it is in vertebrates.

Great Black Wasp

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20 responses to “Tay Meadows Tidbit – Great Black Wasp

  1. Wow. I wouldn’t want to find that where I was about to sit down!

  2. Good find, even if accidental. She’s quite beautiful. I had to chuckle at the discovery… Better to see it ahead of time than to find it the hard way!

    And I’ve also discovered BugGuide tends to err on the low side for sizes. Before I realized that, I questioned many IDs simply because I was looking at something much larger than what the guide offered.

    • It certainly is, Jason!
      I suspect that BugGuide’s sizes are just an average, as well, and there can sometimes be considerable variation within a species. Also, we probably tend to overestimate a little when guessing at sizes without using a ruler (at least, I think I do).

  3. hillsteadnatureblog

    Hello! I was weeding the other day and saw one of these lovelies in the garden. Thanks for a neat post.
    Diane Tucker

  4. Maybe you can start a new round of “toilet bowl spider” hoax emails. “Toilet bowl wasp” is just different enough to make it big!

  5. Christine Kapltia

    These sweet giants have been a regular at my back yard “summer sweet bushes” for around 4 years now. I always wondered why they simply appeared – then disappeared. Now I understand. It was a photo by ‘bev wigney’ that gave me their name – and your blog explained their short, but welcome stint at my summer sweet. There are usually about 20 to perhaps 40 every year. I have some quite large ones that may be 1 3/4″. I’m going to try my hand at both still photos and video. I’ll let you know how that works out. I maneuver around them all the time – and have never been bothered. Do they even sting? With the large numbers in my yard each year – I’ve never once been threatened by them.

  6. I am living in the East Bay Area, California, for a few months and one of these gigantic bugs flew into my house today. Thanks to your info I was able to identify it. I captured it with a pint glass and some paper, to closer examine it. It certainly made good work with it’s pinchers, loudly scraping at the paper (and freaking my son out in the process!) while trying to escape. Seeing it fly with it’s back bits dangling low was very intriguing – how such heavy insects fly, I’ll never know. It looks like a bird.

  7. I live in Bismarck, ND and my mother has a butterfly bush in one of her flower beds. Today while I was watching bumble-bees buzz around it I watched a monster beauty stop in to say hello. I had never seen a Great Black Wasp before. What a sight it was. A vast number of species of bees flock to the plant and I have decided that more of them should be planted to help feed such awesome creatures.

  8. Last year (Aug 1st, 2010) I commented on the abundance of Great Blacks who enjoyed my Clethra Summersweet every year. I live in the Springfield, MA area and have not seen even ONE this year. Has anyone else noticed their absense?

  9. One of these guys flew into our house a few minutes ago. It stayed near the window and I was able to help her find her way back outside by closing the inside window and opening the outside window.

    While I’m not too afraid of wasps, the rest of my family are terrified. I don’t mind them outside, but I sure don’t want them inside my house. At least I’m not allergic to their sting – found that out 2 years ago when we had a yellow-jacket infestation in our bedroom.

    I tend to live by the rule, “don’t hurt them and they won’t hurt you”.

  10. Glad I found this site….I have these gentle giants in my central Virginia garden every summer and wondered what they were. I look forward to seeing them every year dining at my celosia flowers which are also just covered with any number of large and small bee species in August. Not seeing as many of them this year though. Yesterday I also saw 2 other giant wasps out there and will have to look them up too as they are gorgeous.

  11. Christine Kaplita

    Anyone know why the Great Black Wasp hasn’t been around this summer (at least in Western Mass). Was it too dry early on? Hope they come back next year – but I wonder if this years eggs didn’t hatch (or survive) will they be back next year?

  12. This just flew into my house. I’m just stting here watching TV then suddenly I see this land on the TV. Sence I didnt know what it was and sence im 12 this sceard me and I ended up shooting at it with a airsoft gun. Luckly for both of us it flew back out the door.

  13. Hi. Have one here, will try for a picture and then let it go. :)

  14. i love that everyone here is all for saving this critter rather than squashing it i was also glad to see that it was referred to as a gentle giant as i have lots of them visiting my barn, my goats don’t seem to mind but they scare the HELLOOOO out of me we have lots of them here in South Dakota in my barn … any non toxic ideas about how i can discourage them from hanging out here????

  15. laurel Johnson

    When I saw this giant in my yard i almost had a stroke, Do they ever sting humans?

  16. Do they nest in the ground ? I see them going into to joint between the concrete they are about 1 1/2 long shiny black /dark blue I live in Mi.

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