Gypsy Moth Spraying

HealthLinkBC File Number: 
Last Updated: 
May 2016

What is the gypsy moth?

The gypsy moth, Lymantria dispar, is a harmful forest pest that can sometimes be found in rural and urban areas in B.C.

The life cycle of the gypsy moth has 4 distinct stages: egg, larva or caterpillar, pupa, and adult. The gypsy moth lays eggs once a year.

The female moth lays eggs, called egg masses, on solid objects such as trees, lawn furniture, cars, trucks, trailers, and campers. Often the egg masses are accidentally transported by people and can travel long distances to other locations before hatching and starting a new infestation in the spring.

Gypsy moth caterpillar Gypsy moth adult
Gypsy moth caterpillar Gypsy moth adult
Photos provided by the Canadian Forest Service

Where is the gypsy moth found?

The species of gypsy moth found in North America originally came from Europe. It was first identified on the east coast of the United States in 1868. Since 1978 the gypsy moth has been found in many parts of southern British Columbia. It has also been found in Ontario and Quebec, and it has been spreading to parts of southern New Brunswick and Nova Scotia for several years.

Monitoring, public awareness, and eradication programs such as aerial spraying have prevented the gypsy moth from permanently living in western North America.

There are also several gypsy moth species in Asia, which could be even more harmful than the European species. Monitoring helps ensure these pests do not enter the country.

Why is the gypsy moth a concern?

The gypsy moth can cause serious damage to many species of trees and shrubs by feeding on their leaves. This loss of leaves, also known as defoliation, can cause trees and shrubs to grow less or cause them to die.

In B.C., the gypsy moth is a serious threat to major fruit producers. It eats the leaves of fruit trees such as cherry and apple trees, as well as specific berries such as blueberries. A gypsy moth infestation in B.C. could also impact other industries including agriculture, the export of lumber, and nursery products.

Human exposure to airborne gypsy moth hairs, silken threads, and skin shed during large-scale infestations have been reported to result in skin rash and possible upper respiratory tract symptoms. However, large-scale infestations are not expected in B.C., so it is unlikely that exposure to the gypsy moth will affect human health.

How is the gypsy moth population being controlled?

Many methods are used to monitor and control the gypsy moth population in B.C. These methods include mass trapping or ground and aerial spraying of the commercial product Foray 48B®.

Aerial spraying with Foray 48B® is the method used for controlling gypsy moth populations over large or difficult-to-access areas. It is also approved for use on certified organic farms.

What is Foray 48B®?

Foray 48B® is a water-based product containing a bacterium called Bacillus thuringiensis variety kurstaki (Btk). Btk is a bacterium found in soil. It is known to affect only caterpillars, such as the gypsy moth larvae, if it is ingested while they are feeding. In addition, Foray 48B® contains a number of inert (inactive) ingredients which improve the performance of the Btk. Many of these ingredients are approved food grade additives. No petroleum products are used.

Foray 48B® is not harmful to people, dogs, cats, fish, birds, reptiles, or insects such as honeybees, beetles or spiders. Btk pest control products have been registered for use in Canada for about 40 years. It is now the most widely used pest control product in the world.

What happens during aerial spraying?

Aerial spraying of Foray 48B® is usually done in the spring between April and June and takes place between 5:00 a.m. and 7:30 a.m. There are 3 separate applications that are done every 7 to 10 days. These applications are usually required to treat the gypsy moth larvae which hatch throughout the treatment period.

Depending on the size of the treatment area, the aircraft used and weather delays, it may take several mornings to complete 1 application. The treatment area may appear larger than it actually is because the aircraft makes turns in areas outside of the treatment area. Spraying is carefully controlled by GPS navigation equipment and only occurs over designated (select) areas.

You may notice a musty smell and spray droplets on hard surfaces and windows after the treatment. Droplets can be removed with water and a bit of scrubbing, but these will eventually disappear on their own.

Treatment information and schedules are provided through a public notice, at least 24 hours before an aerial application project begins, to residents through the local media, the gypsy moth hotline, websites, and email distribution lists. All schools and hospitals in the affected area are notified in writing at least 24 hours before a spray program is initiated. Treatment schedules rely on the weather, so for up-to-date information visit Ministry of Forests, Lands and Natural Resource Operations

Are there any health concerns?

There have been 2 extensive public health monitoring studies in Vancouver and Victoria. The results have not shown any increase in illnesses seen by health care providers or in hospital emergency room visits due to spraying. As well, the monitoring has not shown evidence of harmful effects on children with asthma or those with weakened immune systems.

If you wish to avoid contact with the spray, it is recommended that you stay indoors while your property and nearby areas are being sprayed. You should wait until the spray has dissipated (dispersed) from the air, usually in less than an hour, before going outdoors. If you have health conditions and are concerned, you should speak to your health care provider.

In addition to staying indoors during the spraying, you should also follow standard good hygiene practices. These include:

  • Wash your hands throughout the day, especially after gardening, after going to the bathroom, and before preparing food.
  • Wash all fruits and vegetables before eating or cooking.
  • Maintain home swimming pools.
  • Clean or wipe indoor and outdoor equipment at daycare centers and preschool facilities, as well as covering sandboxes or sandpits when they are not in use.

For More Information

  • Sign up for the gypsy moth email subscription service at Ministry of Forests, Lands and Natural Resource Operations
  • Call the Ministry of Forests, Lands and Natural Resource Operations’ Resource Practices Branch at 1-866-917-5999.

Is it an emergency?

If you or someone in your care has chest pains, difficulty breathing, or severe bleeding, it could be a life-threatening emergency. Call 9-1-1 or the local emergency number immediately.
If you are concerned about a possible poisoning or exposure to a toxic substance, call Poison Control now at 1-800-567-8911.

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