There have been numerous reports this season from lawn care companies who have clients with turfgrass scale. The turfgrass scale nymphs were found in dead patches of grass that did not green up this spring. As the season progressed more damage became evident. A review of our current knowledge of turfgrass scale is included for those of you who have encountered this insect pest.
Turfgrass scale, Lecanopsis formicarium is a relatively new pest of turfgrass in Ontario. It was first identified in home lawns, parks and sod farms in Ontario in 1983 and 1984. It is mainly found in newer subdivisions on lawns which have been sodded. Sodded lawns 3-5 years old are most commonly infested.
Female turfgrass scales are oblong and yellow with broad brown lateral stripes on each side (Figure 1). They are about 1.5 mm wide and 2.5 mm long. Females lay eggs which are surrounded by a cottony mass (Figure 2). The nymphs which hatch from these eggs are minute (smaller than the head of a pin) and red in colour and leave a red stain when squashed.
Figure 1. Dorsal view of turfgrass scale
Figure 2. Cottony mass in which pink eggs of the turfgrass scale are embedded.
Turfgrass scales overwinter as mature nymphs. These become adults in May and June and they produce cottony masses of silk which contain the eggs. The eggs hatch into crawlers in late June and July. At the peak of their activity crawlers climb to the end of leaf blades giving them a reddish hue. They can be disseminated by wind, on pets, on shoes etc.. The crawlers then settle down on the crowns of the turf plant and feed until winter. Turfgrass scales overwinter as young nymphs which are 2-3 mm long and are salmon coloured. Nymphs overwinter in lawn in the crowns of turfgrass plants and thatch.
Even though turfgrass scale has been known to occur in Ontario since 1983 it is still not known how serious a pest problem it is. It seems to be associated with dead patches or thinning lawns which become evident in late spring and which tend to recover in the fall. There are currently no insecticides registered for control of turfgrass scale. Dr. Mark Sears at the Environmental Biology Department, University of Guelph, reports that washing leaf blades with a hose when crawlers are present can be an effective way of removing them from a lawn. They are very fragile and do not appear to survive this treatment.
Acknowledgment: Figures 1 and 2 were obtained from Dr. Mark Sears, Department of Environmental Biology, University of Guelph.
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