Goniozus Wasps

Goniozus wasps can sting, but you’ll never have to worry about that.

Female Goniozus wasp (Jean-Jacques Kieffer) Public Domain

Like many other parasitic wasps, adult Goniozus wasps mostly feed on nectar, sap, and other sweets. The benefit they provide is that they also parasitize pests of almond, apple, citrus, fig, pistachio, walnut, and coconut trees, as well as blueberries, blackberries, grapes, and strawberries.

Navel orangeworm, obliquebanded leafroller, and light brown apple moth caterpillars are favorite egg-laying hosts, giving Goniozus the common name of navel orangeworm wasp. Personally, I prefer Goniozus - in my mind, it’s the Gonzo wasp. These garden helpers also use banana scab moths and several insect pests associated with galls as hosts.

​Goniozus wasp description

There are 20 different Goniozus wasp species, and they all look like tiny flying ants. Walking through the garden, you may simply see a very small, shiny brown or black wasp-waisted insect. Most insects who fit that description are beneficial, so resist the urge to swat them away. Instead, take a moment and see if you can tell what they are up to.

Goniozus parasitism

Similar to cuckoo bird species, which lay their eggs in the nests of other birds, Goniozus wasps are also known as cuckoo wasps because they lay their eggs in the bodies of other insects.

Adult females use their stinging ovipositor (egg-laying tube) to paralyze their victims, injecting hosts repeatedly with venom. The venom of some Goniozus wasps is permanent, but not all. In those cases, the venom only lasts half an hour or so, so she has that much time to transport her victim, mostly by dragging the much larger host, to a good hiding spot. If necessary, she will continue to inject venom over several hours, if that’s how long it takes to get where she needs to go.

​Once tucked safely into a crevice somewhere, some females will feed on the juices of said caterpillar over the next few days, aiding in the development of her eggs. This does not always kill the host. In some cases, the host simply walks away, a little worse for the wear, until the eggs hatch and begin feeding from the inside out.

Goniozus larvae go through several developmental stages over the next 2 or 3 days, attached to their host, ultimately spinning tiny cocoons around themselves before reaching adulthood. Apparently, Goniozus wasps have been observed paralyzing far more hosts than they can possibly use for egg-laying. No one knows why.

​How to attract Goniozus wasps

Beneficial parasitic wasps can be attracted to your garden with insectary plants. Insectary plants provide the food and shelter needed by these garden helpers. Most insectary plants feature umbrella-shaped flowers commonly seen in carrot, dill, cumin, mint, and cilantro, or globe-shaped flowers, such as chives. Allowing these plants to go to seed not only attracts beneficial insects, but seeds then create perpetual, edible crops. Other insectary plants include cosmos, sweet alyssum, yarrow, dandelions, and borage.

Adding these useful plants to your yard looks nice, too!