Invasive Species
Hickory Tussock Moth Caterpillars
Southwestern Public Health (SWPH) advises parents and caregivers to ensure that children in their care avoid touching Hickory Tussock Moth caterpillars. The Hickory Tussock Moth caterpillar is present in Southern Ontario from July to September, at which time it feeds on the leaves of hickory, walnut, ash, elm and oak trees in preparation for overwintering in its cocoon.
How to identify a Hickory Tussock Moth Caterpillar
- white and fluffy
- has black chain-like markings on its back
- has long black hairs that protrude from areas near the front and rear of the caterpillar. These hairs are connected to poison glands which excrete venom on contact
- grows to a length of about 4.5 centimetres
The venom can cause a rash similar to that caused by nettles or poison ivy. Symptoms can range from slight reddening of the skin to a burning sensation with swelling and pain. Some people may experience an allergic reaction which could include nausea.
SWPH recommends that anyone who touches a Hickory Tussock Moth caterpillar wash the affected area with soap and water as soon as possible. In the case of itching or swelling, apply calamine lotion and/or ice packs to affected areas. Individuals who experience more generalized allergic reactions should seek medical advice from their health care provider.
Wild Parsnip
Wild Parsnip, a member of the carrot and parsnip family, is an invasive species commonly found along recreational trails, agricultural fields, and along roadsides in Ontario.
Wild parsnip contains toxic compounds, called furanocoumarins. These compounds can cause serious rashes, burns or blisters to skin exposed to the sap and then sunlight.
The plant poses a risk to agricultural workers, those involved with vegetation control, and to people unknowingly exposed to the plant in the wild.
How to identify Wild Parsnip
- Grows up to 1.5 metres tall
- The single green stem is two to five centimetres thick and smooth with few hairs
- Compound leaves are arranged in pairs, with sharply toothed leaflets that are shaped like a mitten
- Yellowish green flowers form umbrella-shaped clusters 10 to 20 centimetres across
- Seeds are flat and round
If you have small clusters of wild parsnip on your property (fewer than 100 plants), you may be able to manage the plant yourself. DO NOT burn or compost wild parsnip plants that have been cut down or dug up. If possible, leave the stems to dry out completely at the site.
Protecting yourself from Wild Parsnip
- Wear protective clothing, including waterproof gloves, long- sleeved shirts, pants and eye protection, and a disposable spray suit over your normal clothing.
- After working around the plant, remove your protective clothing carefully to avoid transferring any sap from your clothing onto your skin. Wash your rubber gloves with soap and water, then take off your spray suit or outer clothing.
- Wash your rubber gloves again and then take them off. Finally, take off your protective eye wear. Put non-disposable clothing in the laundry and wash yourself immediately with soap and water.
SWPH recommends that anyone who touches a wild parsnip to wash the affected area with soap and water as soon as possible. In the case of itching or swelling, apply calamine lotion and/or ice packs to affected areas. Individuals who experience more generalized allergic reactions should seek medical advice from their health care provider.
Prevention tips
- Learn how to identify wild parsnip and other invasive plants.
- Stay on trails and away from areas known to have wild parsnip or other invasive species.
- Inspect, clean and remove mud, seeds and plant parts from clothing, pets (including horses), vehicles (including bicycles) and equipment such as mowers and tools. Before travelling to new areas, clean vehicles and equipment in a place where plant seeds or parts aren’t likely to spread, such as in a driveway or at a car wash. It’s very important to carefully wash any sap from clothing, equipment and pets.
- Avoid disturbing soil and removing plants from natural areas; they may be rare native plants or even invasive plants.
Giant Hogweed
Giant Hogweed has a scattered distribution across southern and central Ontario. It spreads readily and grows along roadsides, ditches and streams. It invades old fields and open woodlands. The plant poses a risk to agricultural workers, those involved with vegetation control, and to people unknowingly exposed to the plant in the wild.
How to identify Giant Hogweed
- Up to 5.5 metres tall
- White flower clusters widely spaced and can form a flower-head almost one metre wide
- Coarse hairs on stem
The clear watery sap of Giant Hogweed contains toxins that can cause severe inflammation and burns on the skin if you get the sap on your skin and the skin is then exposed to sunlight. Painful blisters may appear within 48 hours of touching the sap and purplish scars may form that last for many years.
Protecting yourself from Giant Hogweed
If you have Giant hogweed on your property, it is recommended that you hire a professional exterminator to remove it. The best time to remove the plant is in late April or early May. If you will be in contact with giant hogweed it is recommended that you wear protective clothing, including waterproof gloves, long- sleeved shirts, pants and eye protection, and a disposable spray suit over your normal clothing.
- After working around the plant, remove your protective clothing carefully to avoid transferring any sap from your clothing onto your skin. Wash your rubber gloves with soap and water, then take off your spray suit or outer clothing.
- Wash your rubber gloves again and then take them off. Finally, take off your protective eye wear. Put non-disposable clothing in the laundry and wash yourself immediately with soap and water.
- In the event of any direct exposure/contact to this plant If you get sap on your skin wash the area well with soap and water. Keep the affected area out of the sun. If symptoms occur, see a doctor.
- If you get sap in your eye, flush your eye with water immediately and see a doctor immediately.
Prevention tips
- Learn how to identify Giant Hogweed and other invasive plants.
- Stay on trails and away from areas known to have wild parsnip or other invasive species.
- Inspect, clean and remove mud, seeds and plant parts from clothing, pets (including horses), vehicles (including bicycles) and equipment such as mowers and tools. Before travelling to new areas, clean vehicles and equipment in a place where plant seeds or parts aren’t likely to spread, such as in a driveway or at a car wash. It’s very important to carefully wash any sap from clothing, equipment and pets.
- Avoid disturbing soil and removing plants from natural areas; they may be rare native plants or even invasive plants.