Gypsy Moth Information

Gypsy moth egg counts in the City of Monona were not high enough to qualify for aerial spraying this year.  However, City Hall is receiving calls from residents who are reporting gypsy moths on their properties. The moths are now in the stage of laying their eggs. One egg mass can produce thousands of caterpillars next spring. Residents who observe gypsy moths on their property are asked to call City Hall at 222-2525. Do NOT scrape off the egg masses from your trees because the City's forester will need to visit your property to count the masses. By the end of August, the forester will report Monona's counts to the suppression program, and those counts will be used to determine whether Monona qualifies for aerial spraying next spring. There is a spray called Golden Pest Spray Oil that can be sprayed directly on the egg masses but WAIT UNTIL AFTER the first frost.

Suppression Program


The City of Monona participates in the State of Wisconsin's gypsy moth suppression program. The program aims to control the population of this pest, which naturally explodes to very high numbers (called outbreaks) about every 10 years. During outbreaks, the caterpillars are a nuisance and can strip trees of their leaves, defoliating entire neighborhoods or forests by late June. Most healthy trees can survive one such defoliation, but trees that are weak or stressed prior to defoliation may die.

Homeowners who are considering insecticide treatments on their properties should contact an arborist or tree service. The Wisconsin Arborist Association has a list of certified arborists available. Additional businesses offering insecticide treatments may be found in the phone book under Tree Service. Homeowners can also purchase insecticides (some applied as a soil drench) at garden centers and large retailers.

Gypsy Moth Life Cycle

gypsy moth life cycle