Winter and early spring scouting for Gypsy moth egg masses has indicated EPIC levels of the moth larvae can be expected in much of southern Ontario this year!
In 2020, the Ontario Ministry of Natural Resources and Forestry (see above) observed record-breaking areas of defoliation in southern Ontario since the moth’s introduction over 50 years ago. Nearly 600,000 hectares of trees were defoliated by this pest last year, beating the original record of 350,000 hectares in 1991.
Although over 300 species of trees have been identified as hosts of the Gypsy moth, they are mostly likely to be found feeding on the foliage of Acer (except Acer rubrum), Betula, Fagus, Quercus, Populus, Prunus, Salix, Tilia, and the evergreen, Picea pungens.
Get ready to manage young larvae (black head capsule, less than 2.5 cm long) with foliar applications of the bioinsecticide Bacillus thuringienesis subsp. Kurstaki (B.t.K., Bioprotec, Dipel, Foray, ReVokBTK, Thuricide HPV, Thuricide 48LV). High value trees may also be injected with TreeAzin (see label for directions). Later instar larvae may be managed with products containing permethrin (e.g. Dragnet in the landscape, Pounce etc. in the nursery) or spinosad (e.g. Success). See the MOECP “Allowable List” for pesticide applications in Ontario by CLICKING HERE.
IN THE COMING WEEKS: First instar Gypsy moth (Lymantria dispar) larvae will likely be hatching (like these above from 2019) earlier than usual this spring, due to unseasonably warm temperatures in the last several weeks.
After hatching, larvae will climb to the top of the tree, produce a silken thread and take a ride in the wind in hopes of landing on a delicious botanical host.
For great images and management information check out our FREE scouting App Bugfinder, on Apple and Google Play!
