The spongy moth (Lymantria dispar) is an invasive insect that could harm urban forests and British Columbia fruit producers. It attacks and damages over 300 different trees and shrubs. It was formerly referred to as gypsy moth. Originally from Europe, it has been found in Canada for over 100 years but has not been established in Western regions.
The life cycle of the spongy moth has 4 distinct stages: egg, larva or caterpillar, pupa and adult.
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| Caterpillar | Adult female (white) and male |
Photos provided by the Canadian Forest Service
The adult female spongy moth lays eggs in masses between August and September. Egg masses can be laid on numerous different surfaces, including trees, lawn furniture and even on the underside of vehicles, where they can be unintentionally transported over long distances if items are moved.
Spongy moth has been detected in many parts of southern B.C., but management efforts have prevented its establishment. It is established in Eastern Canada including Ontario, Quebec, New Brunswick and Nova Scotia.
Spongy moth larvae damage plants by eating the leaves of trees and shrubs. This can lead to issues like slowed or stunted growth, stem deformities or death of the plant.
In B.C., the spongy moth could be a serious threat to major fruit producers. It eats the leaves of many fruit trees as well as specific berries such as blueberries. An established population in B.C. could also impact other industries such as agriculture, lumber and plant nurseries.
Human exposure to airborne spongy moth hairs, silken threads and shed skins during large-scale infestations have caused allergic reactions. Examples of symptoms include skin rash and possible upper respiratory tract symptoms.
The goal in B.C. is “eradication” (complete removal), to prevent populations from becoming established. While spongy moth populations are detected yearly in B.C., the insect has not become permanently established due to successful eradication efforts.
Many methods are used to monitor and eradicate spongy moth introductions. These methods include ground and aerial spraying of the commercial product Foray 48B.
Foray 48B is a water-based product that contains a bacterium called Bacillus thuringiensis variety kurstaki (Btk). You can find Btk naturally in the soil and it only affects moth and butterfly larvae when they consume it. Foray 48B also contains some inactive ingredients that improve the performance of the Btk. Many of these ingredients are approved food-grade additives. No petroleum products are used.
Foray 48B is generally considered not toxic or harmful to people, dogs, cats, fish, birds, reptiles, or non-target insects such as honeybees, beetles or spiders. Canada has registered the use of pest control products containing Btk for over 65 years. It is the most widely used pest control product in the world and can be used to treat pests on certified organic fruit and vegetable farms.
Aerial spraying of Foray 48B for spongy moths is completed between April and June. There are 3 separate applications every 7 to 10 days between 5 and 7:30 a.m. The separate applications target the spongy moth's larval stage as they hatch. Treatment schedules and duration may change based on the aircraft, weather and area size.
Spraying is carefully controlled by GPS navigation and only occurs in carefully delineated treatment areas. The aircraft may make turns outside the treatment area, making the area size appear larger than it is.
You may notice a musty smell and spray droplets on hard surfaces and windows after the treatment. You can remove droplets with water and a bit of scrubbing, but they will eventually disappear on their own.
Residents receive treatment information through postcards, newspaper articles and media information bulletins in January and again in March or early April. Signs are posted around all treatment areas at least 48 hours before spraying begins and signs are updated at least 24 hours before the second and third sprays. Local media, the spongy moth hotline, websites and email lists also communicate this information. All schools, daycares, care homes and hospitals in the affected area are notified in writing within the same period.
For up-to-date information, visit the Ministry of Forests website: https://www2.gov.bc.ca/gov/content/industry/forestry/managing-our-forest-resources/forest-health/forest-pests/spongy-moth
Health Canada's Pest Management Regulatory Agency evaluates all formulations of Foray 48B for potential health effects and allergic-type reactions. Results show no increase in adverse illnesses reported by health care providers, although a small number of self-reported adverse effects have been reported to Health Canada. Any adverse effects can also be reported directly to Health Canada via their Public Engagement Portal: https://pest-control.canada.ca/public-engagement-portal/en/forms. If you feel concerned, talk to your health care provider.
If you wish to avoid contact with the spray, close your windows the evening before aerial spraying starts and stay indoors while your property and nearby areas are being sprayed between dawn and 7:30 am. You should wait until the spray has cleared from the air before going outdoors, usually after about 1 hour.
It is also important to practice good hygiene by washing your hands after being outdoors and washing produce from affected areas.
Call toll-free in B.C., 8-1-1, or 7-1-1 for the deaf and hard of hearing to get personalized assistance. Speak to a navigator who can guide you to reliable health information or connect you with a health professional. Translation services are available in over 130 languages.
