Alert: Snowbush Spanworm

Snowbush Spanworm
Snowbush is a popular landscape plant used in a variety of landscapes in Pinellas County. Its fast growth and multi-color appearance make it desirable as a hedge or screen.

Until recently this plant has had few if any problems. Currently the plant is under pressure from the Snowbush Spanworm (aka inchworm). This small caterpillar feeds on the plant and will completely defoliate the plant.
In most instances I have observed, when the foliage is all gone the Spanworm will turn to munching on the bark. Foliage of Snowbush

The leaf eating is a problem because the plant is denuded – a plant desired for its foliage is of little value with no foliage! The end result after the spanworm is completed its life cycle, is the plant will foliate.

However, the “girdling” effect of the bark eating will kill terminal branches and sometimes the entire plant.
Defoliated Snowbush by Spanworm
All of this is a recent phenomenon. Prior to 2006, it was rare to have any problems with snowbush in Pinellas County. This recent problem can be a simple imbalance in the predator/prey for these rascals or a population “bloom” of the spanworm.

Solution: The spanworm is easily controlled with available insecticides. The adult – the White Tip Black Moth is of no harm (other than laying eggs) and in a swarm can be attractive. White Tip Black Moth (Spanworm Adult)My best solution is to replace the plant with a plant with similar characteristics such as Viburnum or Eleagnus – depending on the application. The logic for replacement versus treatment is simple: economics! Replacement to an alternative plant is cheaper than treating a reoccurring persistent problem. Reactive or as needed treatments will cost approximately $60.00 minimum. A preventative program will require a minimum of 3 treatments per year at a cost of a minimum of $60.00 per treatment? A replacement shrub would cost less than $30.00 (delivery, removal of existing and planting).