Cankerworms & Tent Caterpillar Control Program
There are three main components to the City's cankerworm control program.
Step 1 - Monitoring
More than 400 traps are placed on various trees throughout the city to monitor the populations of adult male and female cankerworm moths in each area. Cankerworm counts are done on the bands during the spring and fall emergence periods to determine which areas have the highest level of cankerworm concentration for a particular year, and require spaying to control these populations.
Step 2 - Spraying
City crews spray City-owned trees in areas with high concentrations of cankerworms. Areas identified as having higher population levels are sprayed first and as time allows we move to the next level of infestation, in decreasing order of trapped adult concentrations. Spraying is done from mid-May to mid-June when the worms are hatching and feeding on trees. A commercial product containing BTK is used. BTK affects only worms and is non-toxic to other insects, birds, animals and humans. The worms eat the product, stop feeding in 2-3 hours and die in a few days.
The City does not go out to an individual house to spray the trees or spray private trees. Those that have sensitivities can call the Pesticide Advisory Line for information on where and when the City is spraying. Residents are asked to move their cars off the streets while their areas are being sprayed.
Step 3 - Public Awareness
Residents are encouraged to band private and City trees during the spring and fall emergence periods. Tree banding can reduce or manage populations and reduce the need for spraying. Banding trees controls cankerworm populations by trapping wingless female cankerworms as they crawl up the tree to lay their eggs. You should band your trees from late March to mid-May and again from early September to mid-November to catch the cankerworms moths at both the times they are emerging from the soil. It is important to band all trees in an area or else cankerworm larvae could move from unbanded trees to banded trees. Please do not leave bands up longer than recommended as it can do more harm than good to the tree.