Biological Control Agents Have Own Agenda

REGINA - Jul 3/01 - STAT -- The timing of using biological controls to attack problems such as leafy spurge are set by the agent and not the needs of the farm, reminds Saskatchewan Agriculture and Food. In the case of the leafy spurge beetle, now is the time for their co-operators to act.

The spurge beetle is a natural predator of leafy spurge, a noxious weed that can dominate pasture grasses and, if grazed by cattle, causes scours and mouth blistering. The adult beetles emerge in late June or early July, feed on the foliage and mate.

The females lay their eggs, up to 300 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.

"To start a new beetle colony, therefore, land owners 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," says Garry Bowes, noxious weed coordinator with the Noxious Weed Program. "This collection should be carried out 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."

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