Calico Scale

Calico scale (Eulecanium cerasorum) is notorious for raining large quantities of sweet sticky honeydew onto the leaves and stems of its host tree as well as onto understory plants, sidewalks, parked cars, slow-moving gardeners, etc. Indeed, my glasses became speckled with tiny honeydew droplets while taking pictures for this Alert.

Calico scale (Eulecanium cerasorum) is notorious for raining large quantities of sweet sticky honeydew onto the leaves and stems of its host tree as well as onto understory plants, sidewalks, parked cars, hapless gardeners, etc. A dingy patina is added when the honeydew becomes colonized by black sooty molds.

Calico scale (Eulecanium cerasorum) eggs located beneath helmet-shaped females are just about finished hatching in southwest Ohio. As soon as the 1st instar nymphs (crawlers) appear, they make their way to the undersides of leaves where they settle along leaf veins and use their piercing-sucking mouthparts to tap into the phloem vessels.

Calico scale (Eulecanium cerasorum) females spend the winter as small, crusty, flattened late instar nymphs (crawlers) stuck on plant stems. They look nothing like their mature form and may be overlooked or misidentified. They first make their true identity known when they start pumping out impressive quantities of honeydew.

Calico scale eggs located beneath helmet-shaped females are beginning to hatch in southwest Ohio. This life cycle event happens quickly; the small number of 1st instar nymphs that I spotted yesterday will soon become a horde. Unlike armored scales, all nymphal stages of this soft scale are mobile, so nymphs can be called "crawlers" throughout their development.

Calico scale females spend the winter as small, crusty late instar nymphs (crawlers) stuck on plant stems. Although clearly evident, they may be missed by the uninitiated. Everything changes in the spring when the females "puff-up" as they mature and start pumping out impressive quantities of honeydew.

Infestations of the non-native Calico Scale can be difficult to detect during the growing season. However, clusters of crawlers on blackened stems coupled with dead females are key diagnostic features for spotting calico scale at this time of the year.

Calico scale eggs located beneath helmet-shaped females are hatching in southwest Ohio and the 1st instar nymphs (crawlers) are on the move. Unlike armored scales, all nymphal stages of this soft scale are mobile, so nymphs can be called "crawlers" throughout their development

Overwintered calico scale (Eulecanium cerasorum) females are now "puffing-up" and pumping out impressive quantities of clear, sugary honeydew in southwest Ohio. The appearance of the globular, helmet-shaped females coupled with complaints of trees oozing sticky goo makes this life-stage important for detecting new infestations. All other life-stages are much less obvious.

Some of the most productive scouting for insect tree pests occurs once trees lose their leaves in autumn.  If effective pest suppression tactics can't be applied in the fall, detecting insect pests at this time of the year will at least allow you to plan ahead for next season.