What is the spongy moth?

The spongy moth (Lymantria dispar) is an invasive insect that could harm urban forests and British Columbia (B.C.) 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.

Where is the spongy moth found?

You can find the spongy moth in many parts of southern B.C. It is established in Eastern Canada, including Ontario, Quebec, New Brunswick and Nova Scotia.

Why is the spongy moth a concern?

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 has caused allergic reactions. Examples of symptoms include skin rash and possible upper respiratory tract symptoms.

How is the spongy moth population controlled in B.C.?

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®.

What is 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 not toxic or harmful to people, dogs, cats, fish, birds, reptiles, or non-target insects such as honeybees and beetles, or spiders. Canada has registered the use of pest control products containing Btk for about 40 years. It is the most widely used pest control product in the world and can be used on certified organic farms.

What happens during aerial spraying?

Aerial spraying of Foray 48B® for spongy moths is completed between April and July. There are 3 separate applications every 7 to 10 days between 5:00 a.m. 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 the carefully delineated treatment areas. The aircraft may make turns outside of the treatment area, making the area size appear larger than it is; however, no spraying occurs outside of the delineated treatment area.

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: www.gov.bc.ca/spongymoth.

Are there any health concerns?

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. If you feel concerned, speak 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. You should wait until the spray has cleared from the air before going outdoors, usually after about 1 hour.

For more information

• Sign up for the spongy moth email subscription service on the Spongy Moth News webpage: www.gov.bc.ca/spongymoth-news 
• Call the spongy moth 24-hour information line: 1-866-917-5999
• Island Health Video: “Spongy Moth Aerial Spraying: Is It Safe?” www.youtube.com/watch?v=FzTSmsxkJtc