One of the greatest challenges to wildlife, homeowners, foresters, townships and commercial growers and loggers is the invasion of non-native and invasive species that destroy natural habitat and compete for food with beneficial native plants and animals. Questions that needs to be asked when encountering an unfamiliar species:

Exotic Species: "Organisms that have been moved from their native habitat to a new location are typically referred to as non-native, non-indigenous, exotic or alien to the new environment" (National Management Plant, Jan.2001).

Invasive Species: "An invasive species is 1)non-native to the ecosystem under consideration and 2) whose introduction causes or is likely to cause  economic or environmental harm or harm to human health" (National Management Plant, Jan. 2001).

How do these invasive and non-native plants arrive in a particular ecosystem? By several means, which include: intentionally imported and accidentally released, traveling with a commodity, found with transportation equipment or packaging, imported without proper authorization and unknown methods.

Unfortunately, once they are here it needs to be determined what criteria they fit:

There are several "levels" of invasiveness; high, moderate and widespread. Widespread species tend not to be much of a problem. Highly Invasive species tend to get media attention and state and county money towards suppression or eradication programs. There may be local restrictions, county, state or federal regulations regarding a specific invasive or exotic species.

How does one control an exotic pest? Several methods apply: Education, Chemical controls, Biological controls, Mechanical controls and Restoration.

1. Education: Accurately identifying host and pest by monitoring, trapping and/or research. The use of Integrated Pest Management (to help understand complex biological systems before using other controls). Asking questions and seeking answers.
2. Mechanical Controls: Pruning/cutting our infected areas, traps or barriers, use of light, sound, heat or cold to reduce infestation, hand-picking insects, nets, fences or screens
3. Pesticides as a Control: Use of naturally derived or synthetic chemicals that kill, repel, attract, sterilize or interfere with normal behavior or development of pests. Pesticides are either general use or restricted use (not for homeowners). For the proper use of the pesticides - READ THE LABEL! Understand the type and formulation you choose to use. Also consider the toxicity and health effects of pesticides on human, animal and environment. Consider RESISTANCE: pest become resistant to chemicals usually when dosage is increased (more pressure to survive). The greater number of generations of a pest usually mean the greater change to resistance.
4. Biological Controls: Use of natural enemies such as predators, pathogens or parasitoids. They are slower to control the pest but result in a more stable environment. Often self-regulating. Their success depends on proper weather conditions and topographic features.
5. Restoration: Plant resistant varieties. Use cultural controls - routine management practices. Practice good sanitation. Restrict human activities. Possible laws and regulations may apply.

How about some examples? The following are invasive and/or exotic species found in Michigan. Many of them are serious problems throughout the United States and other parts of the world, too. Check out the links following the examples to find out more information about each species or for information in your area.

Purple Loosestrife   

Native to Europe

Invaded North American wetlands and every watershed in Michigan.

Thick strands block water access, take over ponds, reduce food and habitat for wildlife

Management using biological control (three types of beetles) somewhat successful.

Dutch Elm Disease

Fungus introduced to the U.S. on diseased logs from Europe before 1930.

Spread by elm Bark beetles that pick up spores then visit healthy trees.

Also spread by grafted root systems.

Symptoms: wilting, yellow leaves, steams develop dark streaks.

Death of an ideal street tree.

Emerald Ash Borer

First Discovered in June 2002

Dark metallic green, 1/2 inch long present from May to late July. The larvae are white and found under the bark. A serious wood boring pest. Native to Asia (China).

Has already killed millions of ash trees in Southeastern Michigan counties (Livingston, Macomb, Oakland, Wayne, Washtenaw, Monroe) and Windsor, Ontario, Canada. Also been found in Ohio.

Asian Multi-Colored Lady Beetle

Native of Asia

Highly beneficial predator of aphids 

Enters buildings in the fall to

Becomes a nuisance when population rises

Very Photopositive

Usually does not bite - but you can get an allergic reaction to the spurs on their legs

Beech Bark Disease

Beech scale wounds cause  Nectria fungi to infect trees

Introduced into Nova Scotia in 1890 on imported nursery stock

Attacks American and European beech

Weak trees = beech snap

 

Pine Shoot Beetle

Discovered in Ohio in 1992 - established for 10 years?

Eurasian Bark Beetle

Attacks Scotch, Eastern White, Loblolly and other pines in North America

Feeds on shoots

Usually attacks stressed trees

Usually takes several seasons to kill trees

 Oak Wilt

Scientists unsure if this is an exotic or native pathogen

Infects Red, White and Texas Live Oaks

Identified in 1944

Fungus invades vascular system disrupting water from roots to canopy

Leaf curling/discoloration the first sign of infection

Death can occur in one year

Picnic beetles carry the fungal spores to new areas

Dogwood Anthracnose

Fungal disease infects and kills flowering dogwood

Origin unknown

First discovered in 1978

Affected laves may have tan spots with purple borders

Key symptoms: twig dieback, loss of leaves, cankers, epicormic shoots

European Gypsy Moth

Established in Massachusetts in 1869

Has now spread throughout eastern U.S.

Preferred hosts include oaks, aspen, birch, black cherry, willow and basswood

Feeds on 300+ deciduous trees

Causes severe defoliation and annoyance to homeowners

White Pine Blister Rust

Affects 5 needled pines plus currants and gooseberries

Asian pathogen came to U.S. between 1889 and 1910

Complex life cycle

Symptoms include red needles, dead branches, orange spores on trunk and cankers on branches

West Nile Virus - An Exotic Microbe

Directly Involves birds and mosquitoes

First isolated in 1937 in Uganda

First outbreak in N.Y. in 1999

Symptoms more sever in people/animals with weakened immune systems

Humans, many species of birds, bats, horses, dogs and cats have tested positive

As of 2003, Michigan reports 528 cases and 46 deaths (with a 12% death rate)

What about invasive plants? These are definitely a pest to the gardener and wildlife enthusiast.

Examples of Highly Invasive Plants

Examples of Moderately Invasive Plants

Examples of Widespread Non-natives (to the Eastern U.S.)

The following pests are not found in Michigan (yet!) but have been found in the United States. It may just be a matter of time before they travel to your area. That's why it's important to practice good sanitation, use Intergraded Pest Management, educate yourself on pesticides and seek extension office, the department of agriculture, forestry or other county office for more information and help.

Asian Long-horned Beetle

Native to china and Korea

Entered the U.S. via packing material

Established in New York City 1996

Eradication efforts in Chicago

Wood borer prefers Norway Maple but also attacks birch, elm, poplars and willow

Red Haired Bark Beetle

Found in New York

Prefers pines

Difficult to distinguish from native bark beetles

Mass attacks stressed trees

Butternut Canker

Fungus thought to be exotic

Only attacks Butternut trees

Discovered in 1967 in Midwest

Cankers appear around leaf scars and buds

Crown dieback occurs as trees die

Nun Moth

Found in U.S.

Prefers conifers but will attack deciduous trees

Causes widespread defoliation (similar to Gypsy Moth)

Eggs are laid in clusters

Very photosensitive

Often found on docked ships (attracted to the flood lights)

Sudden Oak Death

Found in California in 1995

Caused by a Fungus (maybe an exotic)

Causes bleeding cankers and fading foliage

Spread by rainwater, infected wood and soil

Attacks several species of oak

Asian Gypsy Moth

Serious pest feeds on 600 + deciduous trees

Causes damage very similar to European Gypsy Moth

Females can fly up to 40 kilometers

Males look very similar to European Gypsy Moth

Found in

Balsam Woolly Adelgid

Attacks fir trees

Originally from Europe

Sap-feeding

Excretes fluffy, waxy filaments around their bodies, hence "woolly"

Heavy infestations kill trees

Brown Spruce Long-horned Beetle

First discovered in 1990 in Nova Scotia

Native to Europe and Japan

Wood-boring

Attacks only healthy trees

References and Resources

Send mail to biocentriceducation@lycros.com with questions or comments about this web site.
Last modified: 07/29/03