It seems like I am seeing more wasps than usual buzzing around my garden. I don’t remember this being the case before. Do I have a problem? BG

I have to admit that I used to do my best to eliminate the wasp population from around my home and garden but then I learned that wasps like other insects have a purpose, some are even considered beneficial for gardeners. Since then, wasps are welcome visitors to our home landscape.

One of the wasps that fit into the “good guy” category is the Braconid Wasp. These wasps are small and rarely grow to over 1/2” in length. They are dark in color with 4 transparent wings. The braconid wasp is considered a parasitic wasp, meaning that they use other insects to serve as hosts for their young. Even though the braconid wasp will use other insects for this purpose, the host that gardeners will most likely recognize is the tomato hornworm.

Females have a long and sharp ovipositor (the part of the body used to deposit eggs). Once a female braconid wasp finds a hornworm caterpillar, she injects up to 60 eggs under the skin of the hornworm. When doing this she also injects a virus called polydnavirus. This virus makes it harder for the hornworm’s immune system to fight the presence of her eggs. In addition, the wasp eggs release a hormone that inhibit continued development of the hornworm so that it continues to remain a host for her young.

Once the wasp eggs hatch, the begin to feed on the tomato hornworm. Once they are mature, they chew their way out of the hornworm, spin a small cocoon, and begin the pupation process. After the adult wasps emerge from their cocoons, the hornworm dies.

Gardeners become aware of this phenomenon when they notice a hornworm covered in these tiny cocoons. I must admit our first impulse upon seeing this would likely be to grab our big boy or big girl pants and our gloves to then remove this unusual looking hornworm from our garden. But don’t do that. Just leave it and let nature take its course. When you do this, you will be enabling a new generation of braconid wasps to help defend your tomatoes against future tomato hornworm infestations.

Paper wasps are probably the wasp most of us are familiar with. We have seen their umbrella shaped nests under the eaves of our homes or any number of other places. Even though paper wasps can sting if disturbed, when we see then they are likely out there minding their own business looking for food for their young.

Paper wasps can be yellow, brown, red, or black depending on the variety. All are usually about 3/4 of an inch in length. Interestingly, their nests are made of chewed up wood and plants mixed with saliva.

New wasp colonies begin to appear in spring when the females emerge from their hibernation sites and begin to build their nests. These colonies usually reach their peak size in late summer or early fall with 20 to 75 wasps making nests that vary from 3 to 10 inches in diameter. Fall is the time wasps are out and about seeking mating partners. After mating, the males die, leaving the females to search for an overwintering site.

These wasps serve as pollinators as they feed on nectar from flowers. They are considered beneficial because they will capture a variety of caterpillars from the landscape to take back to the nest to serve as food for their young. Their favorites would include hornworms, loopers, armyworms, and corn earworms. They will also dine on beetle larvae and flies.

Another interesting wasp you might see in your garden is called the Cicada Killer wasp. This particular wasp is one of the largest in North American growing up to 2 inches in length. That right there is a sizable wasp.

Cicada killer wasps create underground burrows for their homes. These burrows are typically located near a tree that plays host to cicadas.

They are called cicada killers because they can paralyze cicadas with their sting. Oftentimes they can do this mid-flight. Once paralyzed, the wasp will carry the cicada back to its burrow.

Once the cicada is relocated to the burrow, the female will then deposit an egg on the cicada then place both in a cell in the burrow. Within 2 to 3 days, the egg hatches and begins to feed on the paralyzed cicada.

Cicada killer wasp burrows have an opening of about 1/2 inch in diameter and will be several inches deep. Typically, you will see a mound of dirt surrounding the entrance. On occasion, a skunk will stumble upon one of these burrows and feed upon the cicadas and the wasp larvae.

Even though wasps sometimes get a bad reputation, they are nevertheless integral parts of our environment and ecosystem. See you in the garden.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org.

Photo Gerald J. Lenhard, Louisiana State University, Bugwood.org