Wednesday, August 18, 2010

Wasp Wednesday: Chlorion aerarium

I think the first time I saw specimens of the Steel Blue Cricket Hunter, Chlorion aerarium, was in the collection at Oregon State University in about 1979. I remember being somewhat surprised that the species even occurred in that state, but here it was, all impressive in metallic teal. The specimens dated back at least a couple of decades or so, but I hoped I could eventually find specimens myself.

This magnificent wasp is frequently confused with the Blue Mud Dauber which I wrote about last week. Both are in the family Sphecidae, and indeed they can sometimes be difficult to tell apart in the field, especially the males. Chlorion aerarium is generally a significantly larger wasp, much brighter in color (though a deep metallic violet blue in much of eastern North America), and less hairy than the Blue Mud Dauber. The antennae of Chlorion originate lower on the face, and the mandible has a single tooth (the mandible of Chalybion is simple). Obviously, one can’t easily examine live specimens at close range to note those more subtle characters. Not without getting painfully stung, anyway.

The Steel Blue Cricket Hunter is so named because the solitary females hunt crickets of the family Gryllidae as prey. Watch for the females scouring the ground and peering into nooks and crannies in search of crickets. Once she locates one, she stings it into weak paralysis and flies it or carries it to a simple burrow she excavated previously. She sometimes chooses to dig her own burrow from inside the entrance of a cicada killer burrow, oddly enough.

The burrow may terminate in more than one cell (multicellular burrows may even be the norm). The female places several crickets in each cell, closing the cell with a plug of soil between forays. A single egg is laid on one of the victims. The larva that hatches then consumes the cache of crickets.

Both genders fuel their frenetic activity mostly on fermenting plant sap oozing from wounded shrubs. That is certainly the case here in Arizona where they can congregate by the dozens on oozing Desert Broom plants (Baccharis sarothroides). All of my images here are from such circumstances. Only rarely does this wasp visit flowers for nectar.

While I have found this species to be common and widespread over most of the United States and adjacent southern Canada, I still remember well my first encounters with them back in The Dalles, Oregon, in the Columbia River Gorge. I actually took a Greyhound bus from Portland to explore the sandy high desert habitat there and found many species of wasps. A railroad bed ran near the river, among tall grasses, mountain ash trees, and an overabundance of poison oak. It was in this area that I found many male Chlorion flitting among the poison oak.

Emerging from the tall grass at the very edge of the railroad tracks I saw a female on the ground. She shined like a living jewel, her body in vivid metallic blue with shimmering blue and violet wings that flicked nervously as she searched for prey.

The following autumn at Oregon State I took my specimens to my mentor, the late Dr. George Ferguson, eagerly awaiting his expert opinion. He initially concluded they were merely Blue Mud Daubers. I confessed I was disappointed, having thought they were Chlorion. Dr. Ferguson then put one under his microscope and said “By golly, you’re right! They’re awful small, though.” What music to my ears to be validated by someone I greatly admire to this day.

Common as a given insect might be, there is still a thrill in discovering it for oneself, and if this blog accomplishes nothing else than to nudge a reader into the field in search of his or her own Moby Dick, then I cannot ask for more. Go, find the “bug” of your own dreams, and tell everyone else about it, too.

39 comments:

  1. I have a paper wasp I believe eating my cabbage worms for me.Got a few shots, but they are a good friend now.

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  2. Thank you so much for this post! You helped me identify a female that I found flying a cricket around town. :)

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  3. i think i may have one or more living underneath my garage. glad i found this site telling me what it is...

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  4. I have one of these living in my backyard and it does not seem aggressive, but are they dangerous? Have they been known to bite or sting people and how painful is the sting?

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    1. Solitary wasps in general are loathe to sting unless you physically grab one. I imagine it would be painful, but the venom only weakly paralyzes its cricket victims, so....

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  5. I found it!
    I was in my driveway this morning when I noticed a large bug on my neighbors side wall. It wondered around in short, erratic bursts. When I went to see it turned out to be a large wasp, or hornet, that was chasing one of my sweet crickets. Black winged with greenish iridescent lower body. I had seen one 26 years ago (pinched between the fingers of my then 6 month old daughter) and have always wondered how dangerous that event had been.
    Todays visitor looked more "teal" while I remember the other as being smaller, less tapered at the waist, and more green. Are these two the same species only male and female?
    (Going "organic" in my yard has been an adventure in insects! Paper wasps eating caterpillars even. )
    Barbara

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    1. This species varies greatly in color from bright "teal" as you say, to deep violet. Gender has little to do with it, but the darker ones are found farther north and east.

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  6. We just moved into a house that has MANY of these flying by the back door in the evening. The backyard is very overgrown (I'm working on it) but is there anything else I can do to get rid of these?

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    1. I strongly suspect it is not this species you are seeing, but instead males of the Blue Mud Dauber, Chalybion californicum. Males of that species gather in "bachelor parties" to spend the night in a sheltered spot. Male wasps do not sting. Lastly, I do not give out pest control advice on this blog.

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  7. One lives under my apartment front door it greets me every morning when I step out for a cigarette it scares the crap out of my friends lol

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  8. I have many living in my garage in many old yellow jacket nests. When I first saw them last year, I was curious as they are really pretty and were not aggressive like the previous residents. After I researched what they were, I let them reside in my cricket filled garage and they have resided there ever since, until recently. I noticed that I haven't seen my friends much lately and I can only think that they moved out as they have harvested all the crickets as I do not see them around either.

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    1. I think it is more likely that you are describing the Blue Mud Dauber, Chalybion californicum. They look nearly identical, but the Blue Mud Dauber would be a much more likely garage inhabitant.

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  9. I think I may have seen one earlier today but I'm not sure,but I live in Michigan and a very dark blue wasp was flying near me before I went out for a run, as I am scared of wasps for past expierences I kinda jumped around, I didn't get stung though, but I was wondering if it was the same wasp

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    1. Could have been, but the Blue Mud Dauber, Chalybion californicum, is nearly identical, and would be more common up that far north. Both wasps are solitary and your risk of being stung is minuscule.

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    2. I think there are few in front of my house they are huge and are feeding on flowers om not sure about crickets and they only are arpund thos time of year

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  10. Please help me identify this little guy. Looks like the cricket hunter but has a long stinger like thing.

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    1. Sounds like maybe a female Sirex sp. horntail wasp. The "stinger" would be her egg-laying organ (ovipositor).

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  11. Hello Eric,
    I live in Saudi Arabia, Riyadh City.
    I found one of these in my OFFICE 6 - 8 months back... I let em be, because it didn't seem to be harmful. It would disappear then reappear after weeks or so...
    Now after So many months, I saw 2 of em, and that got me worried if they started nesting... so I hunted one down for study purpose, as I was unaware of this bug type, so I did some research about it and ended up here.
    As iv'e read so far, They don't exist in this part of the world, so I wonder how they ended up here.
    The one I got is pretty much the same as the one you posted on TOP in your article, just that mine ones wings are more transparent with little translucency...

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    1. There are *other* species of Chlorion in other parts of the world, plus many other genera of Sphecidae that closely resemble Chlorion.

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  12. I got stung by one! And OMG! I've been stung before by the average bee and Hornet, but these buggers pack a huge punch! I was close to Lake Erie in a town named Port Burwell. Laying on a blanket outside enjoying the sun. Well I felt a sting. Swept it away with my hand and it was a Steel Blue Cricket Hunter! Well it started out as a bright red mark about the size of a softball. Then burning like gasoline had been poured on area and lighted on fire. Then dizziness, nausea, and sweat started. Had to lay down. It finally passed and I felt a bit better. But where I got stung was RED! Then in a few days it turned BLACK. And I mean BLACK!! Size of a softball and very tender to the touch. It scared me! I had never seen these before. But I now stay far away from them! Not a fun ride! I healed in about 4 to 5 weeks or more. Then the BLACK started to fade away to a normal looking bruise. Nasty!

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    1. I'm very sorry you had this kind of reaction, Bonnie! Our own immune system reaction is often responsible for out-of-proportion agony and severe symptoms. Just be glad you aren't a cricket! Glad you lived to tell, I know allergic reactions are a serious matter.

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  13. I have a wounded tree oozing sap outside my window with a lot, around 20, of what I believe to be these wasps. They are about 2 inches. I live in south eastern Arizona. Does it seem like these wasps or the blue mud daubers? Either was they are beautiful and creeping me out. I have a picture but couldn't see how to attach it.

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    1. Hi, Kathy. This species is very common where you live. In fact, that is where I got these pictures (Arizona). Baccharis (Desert Broom) often oozes sap and that is where I usually see the wasps, plus beetles, flies, butterflies....

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  14. I just moved into my home in Pennsylvania and I keep finding these in my enclosed back porch (they may "all" actually just be the same 1 I've noticed seeing as though I haven't, nor will I, kill it lol). My question is, if it is the blue mud dauber does that mean their appearance could mean there's a black widow spider around?

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    1. No, the Blue Mud Dauber is an opportunist that will hunt all kinds of web-building spiders.

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  15. Also, if it is the steel blue cricket hunter will it sting me or my kids? They know not to touch bees/wasps but im deathly allergic to bees (never been stung by a wasp to know of allergic reaction determination) and I'm afraid if we don't see it and happen upon it by accident, will it sting and how long would I have before a severe allergic reaction?

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    1. Most likely Blue Mud Dauber. No, does not mean you have black widows around. Solitary wasps like these two species sting rarely, unless you grab one or step on one in bare feet.

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  16. Thanks for this resource! Saw one today and based on your behavior descriptions was able to confidently identify it as chlorion aerarium and not chalybion. Beautiful!

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  17. My wife was stung as we were inside the house at 11pm. We live in rural East Texas. It is about 1/2 inch long, completely black with teal translucence. Tapered waist and spiny legs. either striped or ribbed thorax. The sting she compared the sting to a scorpion or a sweat beetle. Is it possible this was a cricket hunter wasp? I have a photo of it, as she grabbed it and killed it to identify what stung her.

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    1. I would recommend taking the specimen to a local entomologist for proper ID. I'm sorry your wife had that experience, regardless of the culprit.

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  18. Thank you for lovely article on this beautiful insect! I just saw one for the first time in my life (here in Las Vegas), and couldn't believe it's gorgeous coloring and size!

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    1. Thank you for the compliment; and thank you for appreciating wasps! :-)

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  19. I believe I was stung by a steel blue cricket hunter this afternoon, and I originally thought it was a blue mud dauber! I was mowing my lawn, I live in the middle of a wide open field, and we have tons of flying bugs. I was just finishing up and I would have noticed a flying bug of this size near me. I didn't realize she was there coming from the ground. I live by the "I don't bother you, and you don't bother me" philosophy. I had been getting bitten by ants while mowing and I felt something much worse than an ant bite! My automatic reaction was to swat my own ankle and then I looked down, and there was the most lovely, shiny and MASSIVE blue wasp I've ever seen. I wish I could attach a picture of her, I did get a good shot. I didn't kill her, nor was my reaction too terrible thankfully. My question is, the loose soil around this area is riddled with ants, would that not bother a wasp?

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  20. I found one of these in my house, I think it was dead on the floor. Scared the heck out of me. 😅

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  21. I would appreciate your help with an ID. This one was about one inch long - is that more likely to be the blue mud dauber? Has the thread waist and deep metallic indigo color. This is in north FL. Thanks.

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    1. Could be either species. Without seeing the specimen, I cannot make a correct identification.

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  22. I’m pretty sure I seen one of these today I live in Louisiana, it was so big and the beautiful metallic blue color I have ever seen it was in my yard it wasn’t flying but almost hopping from tall weed to tall weed. It got my attention bc I was wondering if it was hurt and then I was wanting to know what kind of insect it was because it was so beautiful I had to know more about it I have several of pictures I was able to capture it took my breath away I am completely in love with this wasp ! I do however have a couple of questions, I have grandchildren that play in the yard will these wasp attack or sting them while they are playing? If they they will and if they did get stung would I need to take them to the hospital or what would I need to do? Is they venous to a small toddler ? Thank you for your wonderful blog on these beautiful wasp and have a great day !

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    1. From reading past comments, they’re not aggressive if you leave them alone.
      But if you accidentally step on one or grab it, they can sting in defense.
      I got pretty close to one to take a good look at it on a bush and it didn’t fly at me or anything like yellow jackets do.
      I’d say just keep an eye on the children so they don’t try to touch it and they should be fine.

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    2. Solitary wasps in general are not at all aggressive. The only potential for being stung is if you grab one, or step on one in bare feet. They are much more likely to see you coming and fly away immediately.

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