This week: An introduction to a small gem of a wasp whose vibrant colors will sometimes take your breath away. 

Cuckoo wasps are more common than you’d think, and they’re not shy about spending time on flowers and surfaces that punch up their vibrant coloring. Once you start noticing them, you’re likely to notice more. I often see them scanning dead wood (you’ll learn why later), and their green punches up against the brown.

These wasps in the Chrysididae family are gentle. The females don’t sting, and members of the Chrysidinae subfamily will roll into a ball when they feel threatened. I’ve also seen them curled up on cool mornings. In this position, they expose only their hardened, pitted exoskeleton, and are safer from attack. 

The pits on the exoskeleton, by the way, are what give these wasps their iridescence. Many times, a cuckoo wasp will look to be varying shades of green or blue as it moves and reflects the sun differently. Fittingly, they’re also nicknamed jewel wasps or emerald wasps. Some have green thoraxes and red abdomens and are known as ruby wasps. 

The “cuckoo” in its common name refers to their habit of sneaking into the nest of a host species, sometimes in old, downed trees, and laying eggs there. When the host larva hatches, the cuckoo wasp eats the host larva and any food left for it. Then, after the pupa stage, instead of a bee or another wasp emerging from the nest, a cuckoo wasp flies out. 

There are hundreds of species of cuckoo wasps in the U.S. and more than 3,000 worldwide. 

Stay curious!

See more of Karen’s work here.


Cuckoo wasp article from Montana: Accessed 6/19/24. 

A blogger watched a cuckoo wasp lay eggs in a potter wasp’s nest and documented it here: Accessed 6/19/24.