Before peonies bloom in spring their unopened flower buds produce a nectar that feeds a tiny wasp called a Spring Tiphia.
These shiny, black, solitary wasps are about half an inch long and are harmless to humans, but deadly to grass-killing Japanese beetle larvae, commonly called grubs.
After feeding on nectar in May and early June and then mating, the female wasp burrows into the ground in search of grubs to lay her eggs on.
“It’s kind of like the movie ‘Alien,’” said University of Connecticut entomologist Ana Legrand. “It looks for the grub and it will use it for providing sustenance to its offspring. "
A wasp larva will hatch from the egg and kill the grub as it feeds on it.
The Spring Tiphia, originally from Korea, was released in Connecticut between 1936 and 1949, specifically to combat the spread of the invasive Japanese beetle which was first detected in the U.S. in 1916.
Legrand said the female wasp will live for about a month and can lay an egg on up to 50 grubs before it dies.
“Studies have shown that they can live longer or they can have more eggs when they are provided resources,” Legrand said.
If the wasps have easy access to nutrients like nectar in your yard, it’s more likely they can help with pest control.
“They will spend more time looking for grubs rather than spending time looking for these nectar resources far away from your garden,” Legrand said.
Peonies aren’t the Spring Tiphia’s only food source. There are native options such as tulip trees, but they can grow up to 50 feet. So a peony plant may be the best size option for many Connecticut residents.
