Beneficial Wasps and You

(Don’t be scared!) How wasp pollination and predatory efforts are signs of a healthy ecosystem

What is the first thing you think of when you hear, “wasp”? Was it yellow jacket, hornet, fear, nuisance, pain? What about beneficial wasps? Have you heard of them? What do you think they do? For many the concept of a “beneficial wasp” is entirely foreign and difficult to believe. There are actually thousands of species of wasps in the United States alone, with the vast majority being solitary, non-aggressive wasps.

These wasps keep to themselves and provide multiple ecosystem services including pollination, but are especially critical for pest control in our gardens, public lands, and croplands. This month we challenged ourselves to see just how many different beneficial wasps we could find and photograph in our gardens and investigate their roles in our ecosystem.

Wasp species have a complex evolutionary history, and are generally divided into two superfamilies, the Apoidea (which also includes bees), and Vespidae. Of the several Apoid species we found, Bembix (above, on Rudbeckia) are one of the most striking. These Sand Wasps have fluffy faces with brilliant green eyes, and swiftly dig their nests in sandy soil where they progressively provision their larvae with flies over a series of days.

Cerceris (seen here with a friend on Swamp Milkweed), or Weevil Wasp species, are also ground nesters and prey mostly on beetles and weevils, with some species also taking bees and wasps back to their nests.

Among Philanthus species (above on Pycnanthemum, a mountain mint), called Bee Wolves or Digger Wasps, larvae feed on bees provided by the mother. Females cultivate beneficial bacteria in the bases of their antennae that they apply to their brood cells in order to protect from harmful microorganisms, a la antibiotics.

Sphecid, or thread-waisted wasps are very common ApoidsAt Applewood, we found multiple genera that prey on Grasshoppers and Crickets (also known as the Orthoptera family or Orthopterans.) 

The Thread-waisted Wasp genus Prionyx (above, on Buckwheat, Eriogonum spp.) provisions nests with paralyzed adult grasshoppers that they lay a single egg on. 

Isodontia elegans, the Elegant Grass-Carrying Wasp (feeding here on Mountain Mint), is often seen flying with grass blades that they line their nests with, and provision them with crickets and grasshoppers in divided cells within trees, hollow stems or other cavities. 

Sphex are another somewhat larger Thread-waisted Digger Wasp genus that prey on katydids and other Orthoptera. Females are ground-nesters and have pronounced tarsal-rake spines on their forelegs (like extra bristles on their front feet) that help them dig out their nests. They are common visitors to Rattlesnake Master (Eryngium yuccifolium).

Ammophila species (above, on Goldenrod) are Thread-waisted Sand Wasps with particularly long petioles (the “thread waist” connecting the thorax and abdomen), and provision their burrows with paralyzed caterpillars and sawflies that single eggs are laid onto.

Vespidae are another large wasp family that includes the social Yellowjackets and Paper Wasps but also many solitary species, most of whom stock their nests with caterpillars. In our gardens, we found Stenodynerus and Pterocheilus: Potter wasps that are often parasitized by Cuckoo wasps also featured here, which use mud to build their brood cells and mostly feed moth larvae to their young (Stenodynerus in the image above and Pterocheilus below).

One of the glittering jewels of the gardens, Chrysidid, Jewel Wasp or Cuckoo Wasps (above, on Goldenrod) are tiny cleptoparasites, most often parasitizing other wasp and bee larvae. This large family of wasps is actually stingless and the unique pitted surface of their bodies produces their shimmery colors.

Fear not, arachnophobes- Tarantula-hawk wasps (Pepsis species), are a glimmering sight to behold. These large wasps are fond of milkweed (in this case, Broad-leaved Milkweed, Asclepias latifolia), and lay single eggs on paralyzed tarantulas or other large spiders that they bring to their nests. These giants can be intimidating and have a powerful sting, but are gentle and non-aggressive.

Stay tuned for future posts about wasps in agriculture and their other roles as a part of our ecosystemsOf course, these are just a fraction of the beneficial wasps that are workhorses for pest management. Have you seen any of them in your area? Quietly watch and see that these wasps aren’t enemies, but valuable friends.

Multiple thread-waisted wasps on either side of a male Halictus sweat bee and cuckoo wasp. Large goldenrod fronds are often buzzing with diverse assemblages of pollinators.

Beneficial Wasps and You

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What is the first thing you think of when you hear, “wasp”? Was it yellow jacket, hornet, fear, nuisance, pain? What about beneficial wasps? Have you heard of them? What do you think they do? For many the concept of a “beneficial wasp” is entirely foreign and difficult to believe. There are actually thousands of […]

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