Invasive Pests

Saskatoon has a large urban forest which is subject to various tree defoliators. The most common defoliators are spring and fall cankerworms on elm trees; eastern forest tent caterpillars on ash trees; and spruce budworms on spruce trees. The urban forest is also under continual threat by introduced pests such as the newly introduced cottony psyllids, emerald ash borer, Asian long horn beetle and gypsy moth.

Asian Longhorn Beetle

What is the Asian longhorn beetle?

The Asian longhorn beetle is an exotic pest thought to have been introduced from China in wood packaging used in cargo shipments. Adult beetles are large, approximately 2-3.5cm in length. They are glossy black, with up to 20 white markings on their backs. The antennae are longer than the body and have distinctive white to bluish white bands.

What kind of damage is caused by the Asian longhorn beetle?

The Asian longhorn beetle feeds on a variety of hardwood species, but prefers maple, poplar, willow and birch. It is very destructive, feeding on the stem tissue causing structural damage, removing the nutritive rich cambial layer and eventually girdling the tree. Heavy infestations of this beetle will kill healthy trees.

How can I control Asian longhorn beetles?

Preventing the movement of wood materials from areas of infestation is the best way to control the spread of this insect. The Canadian Food Inspection Agency is actively monitoring the movement of the Asian longhorn beetle throughout Canada.

If you have any questions or concerns about the Asian longhorn beetle, please contact the City of Saskatoon, Parks Branch at 975-3300.

Banded Elm Bark Beetle

What is the banded elm bark beetle?

The banded elm bark beetle, thought to have been introduced from Asia, is a serious pest of North American elm trees. Similar to other adult bark beetles, this beetle is quite small, measuring only 3-4 mm in length. They are dark brown or black in colour, with a distinctive dark band across the elytra.

What kind of damage is caused by the banded elm bark beetle?

The banded elm bark beetle is considered a primary bark beetle, meaning that they are capable of killing healthy trees. Elms are their preferred host, but other shade trees such as willow, Russian olive, caragana and various cherry species are attacked. Recent studies have shown that banded elm bark beetles can vector Dutch elm disease, a serious concern on the Prairies. By having the ability to kill otherwise healthy trees, as well as acting as a disease vector, the banded elm bark beetle could prove to be one of the most serious threats to urban forests in North America.

How can I control banded elm bark beetles?

Currently, the only measure being taken for the banded elm bark beetle is an intensive monitoring program by the Province of Saskatchewan. Early results show banded elm bark beetles in communities in southern Saskatchewan. Following the provincial Dutch elm disease regulations and restricting the movement of elm firewood are the most important control measures to prevent the movement of banded elm bark beetles around the province.

Cottony Ash Psyllids

What is a cottony ash psyllid?

The cottony ash psyllid is a non-native pest that was found in Saskatoon in 2006 on black and Mancana ash. This insect is native to central Europe, but has made several appearances in North America, including recent infestations in North Dakota, Minnesota, Alberta and Saskatchewan. To date there is limited information on the biology of cottony ash psyllids. Adult psyllids are small, 3-3.5mm in length, and light green to yellow-green in colour, with black markings. Because of their small size, the presence of cottony psyllids the insect is very difficult to detect.

What kind of damage is caused by cottony ash psyllids?

Browning, yellowing and curling of the margins of ash leaflets indicate a first generation nymphal psyllid population. The curled leaflet shelters the psyllids, which is lined with a white cotton secreted by the insect.

White cotton along the midrib of an uncurled leaf indicates second generation nymphal psyllids.

How do I control the cottony ash psyllid?

If you think that your black or Mancana ash may be infested with cottony ash psyllids, please contact the City of Saskatoon, Parks Branch at 975-3300.

Emerald Ash Borer

What is an emerald ash borer?

The emerald ash borer (EAB) is an exotic pest introduced to North America from Asia. First identified in the spring of 2002 in Michigan and Ontario, the emerald ash borer has become the largest threat to ash trees in North America. The adults are slender, elongate beetles 0.75-1.5cm long. They are metallic coppery green in colour. Larvae are white, flat and slender, with a pair of brown pincer like appendages on the abdomen.  They reside in the stem of the host tree.

What kind of damage is caused by the emerald ash borer?

EAB is a highly destructive pest to most species of ash trees in North America. This pest has killed millions of ash trees in southwestern Ontario, Michigan and surrounding states, and poses a major economic and environmental threat to urban and forested areas in Canada and the U.S.

How do I control the emerald ash borer?

Preventing the movement of wood materials from infested areas is the best practice to slow the spread of the emerald ash borer. The Canadian Food Inspection Agency is actively monitoring the movement EAB throughout Canada.

Avoid importing ash firewood into Saskatoon. If you have any questions regarding EAB, please contact the City of Saskatoon, Parks Branch at 975-3300.

Gypsy Moth

What is a gypsy moth?

The gypsy moth is one of the most serious introduced pests in North America and has recently been found in Saskatoon. Adult females are large and white, while the males are slightly smaller and tan coloured. There are two types of gypsy moth that are of concern. The European gypsy moth was originally introduced in 1868 by a naturalist in Massachusetts for silk production. After escaping 140 years ago, this insect is now established throughout most of eastern North America. The Asian gypsy moth is not established in Canada. There have been several accidentally introduced on cargo ships from eastern Russian, but these were successfully eradicated.

What kind of damage is caused by the gypsy moth?

Gypsy moths prefer to feed on the leaf tissue of oak, willow, poplar, elm and birch trees, however, they will feed on hundreds of species of plants including conifer species. Gypsy moth caterpillars can eat up to 90cm2 of leaves per day, and are capable of killing trees with consecutive years of severe defoliation. In their native area, there are hundreds of predators that will keep populations in check, whereas in North America, there are less than 50. We are not aware if there are any natural predators here in Saskatoon.

How Can I control gypsy moths?

Gypsy moth populations are actively monitored by the Canadian Food Inspection Agency (CFIA). Female European gypsy moths cannot fly, therefore, long distance natural dispersal is not likely. Spread of this pest is usually by importation of infested nursery stock. Plants or firewood should not be imported from areas that may have gypsy moth problems.

If you think you may have gypsy moth feeding on your trees, please contact the City of Saskatoon Parks Branch at 975-3300.

Useful Links

Canadian Food Inspection Agency (CFIA):http://www.inspection.gc.ca