Now is the time to collect leafy spurge beetles to transfer to new locations.
The spurge beetle is a natural predator of leafy spurge, a noxious weed that can dominate pasture grasses and, if grazed by cattle, cause scours and mouth blistering.
The adult beetles emerge in late June or early July, feed on the foliage, and mate. The females lay up to 300 eggs per season below the soil surface near a spurge root.
When the eggs hatch about three weeks later, the larvae feed on the roots, which eventually reduces the spurge population.
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“To start a new beetle colony, therefore, landowners with a leafy spurge problem should collect the adult beetles as early as possible in July because that’s when the females are filled with lots of eggs,” said Garry Bowes, noxious weed co-ordinator with Saskatchewan’s Noxious Weed Program.
Collect them on a warm sunny day with no wind.
“That’s when the greatest number of adults will be found on the tops of leafy spurge plants.”
To ensure a maximum survival rate, Bowes said farmers should first determine the site for a new colony. A sweep net should then be used at an established colony to collect 1,000-5,000 beetles, which should be placed in a bag along with spurge foliage. The taped bag should be taken directly to the new site and left open on the ground.
“If the beetles have to be in the bag overnight, the bag should be kept in a cool, dry place,” Bowes said.
He recommends the black spurge beetle for moist, heavy clay locations, and the brown dot spurge beetle for sandier, drier environments.
Some of the province’s populations are mixed, but Bowes said each kind will find its optimum place.
Landowners who don’t have beetles can contact their local rural service centre to locate the nearest supply.
After a year, a colony is considered successful if more than 25 beetles can be collected in five sweeps.
There should be a noticeable reduction of flowering spurge after two years. Within five years the spurge shouldn’t make up more than five percent of the ground cover.
Successful beetle colonies should be ready for harvest after three full years.
