Lepidosaphes ulmi

 

HOST Aspen, ash, cotoneaster, willow, lilac

DAMAGE/SYMPTOMS Branch dieback can occur with heavy infestations.

LIFE CYCLE Eggs hatch around mid to late May. The crawlers then feed, settle, mate, and produce an armored shell on branches for overwintering. The female produces eggs and remains protected underneath the shell throughout the winter.

MANAGEMENT In small numbers, oystershell scale rarely affects plant health. The scale is typically controlled by natural enemies later in the season. If practical, scrub the branches lightly with a plastic brush. If chemical control is necessary, apply a dormant oil before bud break. Monitor for the crawler stage and follow up with a contact spray if populations are heavy. The systemic insecticide and active ingredient dinotefuran can be applied in early May. The active ingredient imidacloprid is not very effective against hard scales such as the oystershell scale.

 

A Scale infestation on aspen. B Oystershell scale eggs. C Oystershell scale adult and eggs.

 

Scale infestation on the trunk of an aspen tree.    

Oystershell scale eggs.

Oystershell scale adult and eggs.