A Wasp-Benefit Analysis

Posted by: Lisa Mason, Arapahoe County Extension

What is the purpose of wasps?

I am asked this question quite often. Why do we have wasps? What is their purpose? Do we need them?

We have a couple of wasp species that can be a nuisance to people. They tend to give wasps a bad reputation. In reality, wasps are a fascinating, diverse group of insects that play a critical role in our ecosystem!

A beneficial sand wasp (Bembix sp.) hunts caterpillars and flies. They can often be seen visiting flowers for nectar in the summer. Photo: Lisa Mason 

Here are some important facts to know:

• Two species of wasps Colorado are considered a nuisance: The Western yellow jacket (Vespula pensylvanica) and the European paper wasps (Polistes dominula).
• Besides those two species, wasps are a very diverse group of insects with thousands and thousands of species documented worldwide. How diverse? Current science says that beetles (Coleoptera) are the largest group of organisms on the planet representing about a quarter of all described species. However, some research suggests that parasitoid wasps are actually the largest group of organisms but we haven’t been able to document all the species. Here is a fun NPR article on subject.
• Many wasps can’t actually sting including parasitoid wasps and other solitary wasps.
• Most wasp species are solitary insects. Only wasps in the Vespidae family are social and live in colonies. Often, the social wasps are brightly colored to warn predators that they are dangerous. They will defend their nest and sting if needed.
• Many other insects mimic the bright colors of social wasps to protect them from predators. This phenomenon is known as Batesian mimicry. Common mimics include flies in the Syrphidae family, also known as flower flies or hover flies. You can observe these harmless insects in flowers in the summer time.
• Wasps provide valuable ecosystems services to humans because they provide pest control in your landscape. Some wasps are predators and others are parasitoids, meaning the wasps will lay eggs in another host insect and consume the host. Our world would be full of pest insects without wasps!
• You can thank paper wasps for our current paper production industry! In the 1700’s, paper was made from cotton and linen until there was a shortage of those materials. A French naturalist named Antoine Ferchault de Réaumer had observed how paper wasps use wood fibers to make their paper nests, and thought people could do the same thing to create paper. Paper products today are still made out of cellulose fibers from wood (Paulson and Eaton, 2018).

European paper wasp (Polistes dominula). Photo: Lisa Mason

A syrphid fly (Spilomia sp.) that mimics stinging wasps but can't sting. Photo: Lisa Mason 

What about the “murder hornets”?

The Asian giant hornet (Vespa mandarinia), the world’s largest hornet, has received a lot of press recently because a small number of individuals were found in Washington state. While the insect may look intimidating, much of the news media is sensationalized.

I encourage you to read a media interview with Dr. Cranshaw, CSU entomologist. He talks about how calling them “murder hornets” is unnecessary. Many wasps are predators and hunt other insects. The Asian giant hornet is no different. 

Much of the media has focused on how Asian giant hornets preys on honey bees. While they can prey on honey bees if near a hive, Asian giant hornets are generalist predators. They will feed on a variety of insects and will be opportunistic in hunting. They will not specifically target honey bees unless there is a hive nearby. Beekeepers around the country have more important challenges concerning honey bees including the varroa mite.

Will the Asian Giant Hornet come to Colorado?

Short answer: No. We don’t have to worry about the Asian Giant Hornet coming to Colorado for the following reasons:

·       Asian giant hornets thrive in different climate than Colorado. They need low-elevation areas and higher moisture levels.

·       There are many geographic barriers preventing the Asian giant hornet from spreading including the Rocky Mountains.

·       They are unlikely to hitchhike like some other invasive species. 

·       Efforts to eradicate the hornet is Washington are occurring now.

What if I find an Asian Giant Hornet in my backyard?

Colorado has some wasp species that large and may appear to look similar to the Asian giant hornet. These wasps are harmless and common in Colorado landscapes. The two wasps that may look like the hornet include cicada killers and horntails. Both of these wasps cannot sting you. 

Cicada killers target cicadas when hunting and provide the prey to their young.

Horntails appear to have a large “stinger.” This “stinger” can’t sting you at all! It is called an ovipositor, which is adapted to drill into the bark of trees. Female horntails lay their eggs underneath the bark of trees. They don’t harm trees and tend to lay eggs in trees that are already stressed out.

Solitary wasps such as these found in your landscape are not aggressive and should be left alone. 

If you are looking for the identification of a wasp found in your landscape, contact your local Extension office for assistance.

Here is a visual of the Asian giant hornet compared to common, harmless wasps including cicada killers and pigeon tremex horntails. Photo: Texas A&M Extension

Stay tuned for more info on wasps!

Look for future blog posts about wasps! I will discuss the differences between social and solitary wasps, and well as some common and beneficial wasps you might see in your backyard.

Wasps can be scary to people for a variety of reasons, but I hope to article can help instill some appreciation for what all wasps contribute to our ecosystems.