Beautiful Biocontrol: The Scoliid Wasp

Beautiful Biocontrol: The Scoliid Wasp

If, in late summer, you notice a cloud of wasps careening in arcs and figure eights across the surface of the grass, don’t be alarmed and don’t reach for the pesticides.  Celebrate these native beneficials that consume grub larvae and pollinate flowers! They are scoliid wasps– likely Scolia dubia or a close relative.

 

Although scoliid wasps may look intimidating when they congregate, they will only sting humans if severely harassed. Green June beetle and Japanese beetle grubs, on the other hand, have plenty to fear. A scoliid wasp stings a grub to paralyze it, lays an egg on its surface, and provisions an underground cell with additional paralyzed grubs for its larva to eat as it matures. She then repeats this process, dooming additional grubs as live feed for her offspring in other chambers.

 

Your best chance to examine these attractive wasps is while they feed on nectar. They enjoy a wide variety of flowers, including white clover and mountain mint. They have lovely metallic blue wings and a pattern of yellow spots on the abdomen that varies with the species and gender. Their distinctively curved back is the origin of their scientific name– think “scoliosis.”

 

Scoliid wasps’ many common names, including flower wasps, scarab hunters, and scarab hawks, remind us of their multiple functions in our ecosystem and their extraordinary value for gardeners.

Nicole Selby
nselby1@swarthmore.edu
20 Comments
  • Drew Pegon
    Posted at 10:32h, 10 October Reply

    Thanks Nicole. I rarely see these beautiful wasps except when they’re feeding on flower nectar, especially Mountain Mint’s. There are often so many on the plants’ flowers I’ve often thought we should list their flower color as black and red!

    I’ve been threatening to do a proper I.D. for far too long, am grateful for your informative posting, and appreciate them all the more now that I know the wasps’ taste for grubs.

  • Thomas
    Posted at 22:46h, 26 December Reply

    Thanks for sharing, Nicole. Scoliid wasps are parasitic upon larvae of soil-inhabiting scarab beetles. Check out the Campsomeris plumipes species page: http://www.marylandbiodiversity.com/viewSpecies.php?species=6436

  • Marsha Reid
    Posted at 21:13h, 17 June Reply

    How do I get them out of this camper we have inherited, they have become aggressive when I was trying to clean, I haven’t found their nest?

  • Lars Rasmussen
    Posted at 13:52h, 19 June Reply

    Hi Marsha, if you have wasps in your camper, it is probably not Scoliid ones. Scoliids are ground nesting.. You are probably dealing with a nest of Paper Wasps. You may want to look/go after them on a cool early morning when they are less active with a can of wasp/hornet spray and a flashlight. -Lars

  • Charles Ivey
    Posted at 07:28h, 21 June Reply

    I was stung by a blk with yellow on the legs I’m thinking it’s paper wasp they were under my dock,how long will my hand and wrist stay swollen an burn.

  • John Hille
    Posted at 09:57h, 19 August Reply

    Hundreds were swarming over my lawn this morning but not seen in my neighbor’s lawns. I recently sprayed my lawn for June beetles that were swarming in our bushes. I have also had issues in controlling moles in the yard and assumed that grubs were plentiful and the spray would help get rid of the mole’s food source. Just recognized the Scoviid Wasps today. Could they be so plentiful due to my recent attempt at controlling grubs as food source for the moles possibly are forcing them out of the ground?

  • Lennox Castleberry
    Posted at 15:36h, 20 August Reply

    How are they around dogs?

  • Lars Rasmussen
    Posted at 09:01h, 27 August Reply

    I had a report of wasps flying around my Aunt’s yard and I volunteered to check it out before she sprayed them. They were the Scoviid Wasps, so I told them the benefits and she agreed not to spray. She was afraid of being stung but you can walk through an area slowly and not have that happen. I later saw a large population flying in low arcs over a cemetary lawn. John. I doubt the wasps were flying in mass in your yard because you had sprayed earlier. Very possibly they know where the large June and other beetle grub populations are. Lennox, I don’t think your dog will have any issues. They tend to leave our dog alone. It mind depend on how much a dog digs in the lawn! These are such a beneficial wasp and I have planted Mountain Mint on the property to attract them. -Lars Rasmussen Assistant Supervisor for Plant Health

  • Robbie B. Cuellar
    Posted at 15:52h, 05 July Reply

    Really, it is a Beautiful Biocontrol….
    I want to thank you for sharing this!!!

  • Thomas Miller
    Posted at 15:23h, 17 August Reply

    Beautiful wasps. They are no problem to work around. I was amazed!

  • Carol Imamura
    Posted at 10:00h, 24 August Reply

    Thank you for helping me identify these wasps. They recently appeared en mass on my deck where I have large pots of spearmint and peppermint that are flowering. I’m glad to know they are beneficial especially since I had a bad outbreak of Japanese beetles this year I’m sure they’ll take care of them!

  • Patti Silvani
    Posted at 08:10h, 25 August Reply

    How long will they stay and will they come back every year. This in my first year with a small vegetable garden cukes, tomatoes and peppers. 7 plants all together. Thank you

    • Mary Tipping
      Posted at 14:17h, 25 August Reply

      Hello Patti,

      Thank you for inquiring about the scoliid wasp. This wasp generally remains active until the end of the growing season, and only seeks grubs in the soil to use as a food source for their larvae. Rather than fear them, consider them loyal defenders of your lawn and garden since their offspring feed on the grubs of green June beetles and other root-feeding grubs.

      • Becky Robert
        Posted at 14:34h, 25 August Reply

        Hi Patti, they seem to be most active here in Southeast Pa in August. You will also see them in September. I have seen them most years, and expect to see them every late July-August(a welcome sight!).

        -Lars Rasmussen
        Assistant Garden Supervisor/Plant Health
        Scott Arboretum

  • Anthony W. Powers
    Posted at 15:46h, 25 August Reply

    Thank you for the information! Here is another twist to this interesting wasp, the Scolia Dubia. I have a little rancher in semi-rural southeastern Pennsylvania. I have well water and septic with “sand mound” as part of my back yard. It looks like a small hill and not “sand”. I noticed the wasps the summer after moving in, just at the sand mound. Unfortunately I hired an exterminator and he sprayed the mound. Long story unbearable, I’ll never do that again, unless I do more research. Last summer I was laid up with surgery, so I wasn’t as aware of my Scolia’s! They only hang out at the sand mound AND about 30yards away at the flower boxes filled with “mint tea” plants. The mint teas plants were here before I moved in and I haven’t taken the effort to get rid of the plants, YET! The wasps don’t bother me. I’ve walked over the sand mound and they don’t bother me at ALL! Why only the sand mound? I get the mint tea. Are the grubs only in the sand mound? What kind of grubs? I’d love to know more and if I can mow the grass when they are around!!

    • Becky Robert
      Posted at 08:17h, 30 August Reply

      These wasps tend to go after Green June Beetle and Japanese Beetle grubs.
      -Lars Rassmussen
      Assistant Garden Supervisor/Plant Health
      Scott Arboretum

  • Shannon marshall
    Posted at 10:52h, 26 August Reply

    Thanks! I”m pretty sure i have a nest of these guys, at the edge of my lawn. Lol…i decided this is correct, because of the VAST amount of beetles! So… I’ll leave them alone till its cold!

  • Cindy Dorough
    Posted at 10:29h, 29 August Reply

    These wasps have been flying all over my front yard for about three weeks now. Is it safe for me to trim the bushes and use the weed eater when they are active?

    • Becky Robert
      Posted at 08:18h, 30 August Reply

      Yes, it is safe to do yard work when they are active.
      -Lars Rassmussen
      Assistant Garden Supervisor/Plant Health
      Scott Arboretum

  • Kassie Schelling
    Posted at 11:33h, 03 September Reply

    I have planted a lot of mint in my yard here in southeastern PA. Every year when the mint flowers I get these wasps, which I leave alone, bc they leave me alone! Today I finally looked them up and discovered that they are the Scoliid wasps. They are quite beautiful- I try not to spray anything in my yard bc I cultivate flowers for my pollinator friends.

Post A Comment