By Christy Solo – ONPA 1st Place Award Winner for Best Local Column
This week’s crawly is a petite but potent pest controller. Meet Brachymeria ovata an adorable little chalcid wasp with a tongue twister of a genus name (pronounced Bruh-chi-mer-E-ah) – yup. We’ll call them “ovata” for brevity and to avoid spraining our tongues.
There are 26 species of Brachymeria in North America but ovata is one of just a few of those who are well known.
Ovata can be found throughout the United States; “found” is doing some heavy lifting in that sentence. At just 6mm (under one-quarter of an inch), they are hard to spot but they are definitely around. Ovata are most “famous” in agricultural areas and especially here in the west.
Why?
Quick refresher on chalcid wasps, they are itty-bitty parasitoid wasps. This means baby chalcid wasps grow by dining on the eggs, larvae or adult forms of other crawlies. When it comes to ovata kiddos, their preferred food is caterpillars, mostly moth caterpillars.
Ovata have been observed parasitizing around 100 different species of moth pillars, which gives you a good idea of why they are friends of agriculture.
Fun fact: California dedicated about 55K agricultural acres to avocados in 2025 and one of ovata’s favored caterpillars is the pillar of the avocado leafroller moth (Amorbia cuneanum) (who we met in a Crawlies in 2023).
While avocado leafroller moths aren’t a problem here in Oregon, they can be a bit pesty in California and tiny titan ovatas are down south saving your guacamole!
Here in Oregon avocado leafrollers munch on the leaves of madrone and manzanita causing only cosmetic damage while still being a tasty food source for our ovatas.
One example of the power of ovatas’ pest controlling abilities also comes from California. The spring of 2020 saw a boom of California oak moth caterpillars. Much like our oak-munching pandora moths, Ca. oak moths have a population explosion every now and then.
One grove of California live oak trees was completely defoliated by the hungry, hungry caterpillars. Because Ca. oak moths have two generations per season, grove caregivers worried that Gen II would once again defoliate the grove as the adults from Gen I should have hatched out and begun laying eggs just as the Ca. oaks were recovering and sprouting new leaves.
However, leafmageddon 2.0 never arrived because hundreds of ovatas hatched out of hundreds of those oak moth chrysalises instead of moths. Boom cycle stopped.
Fun fact: There have only been four sightings of Ca. oak moths in Oregon, so don’t panic.
Not only do ovatas keep caterpillar booms under control, but they do a bit of incidental pollination on the side. Like most other wasps, adult ovatas feed on nectar and aphid honeydew so you may spot one out and about on a flower or around an aphid colony any time from May through November.
Our pictured ovata was hanging out on my upstairs landing in late September.
Final fun fact: What’s up with the “never misses a leg day” back legs on our tiny wasp? Many different species of chalcid wasps have these raptoral hind legs. There are a couple of theories as to why (the wasps aren’t telling!) One, they help to grip the host so females can lay eggs on them. Two they’re spring loaded and help the wasps jump or spring into flight to escape being preyed upon themselves.
Whatever the reason, they sure look wicked cool!
