Government of Canada
Symbol of the Government of Canada
Skip to content | Skip to institutional links

Common menu bar links

Plants > Plant Pests

Institutional links

Exotic Forest Insect Guidebook 2006

PDF (6,024 kb)

Prepared by:
Troy Kimoto
Plant Health Survey Unit Canadian Food Inspection Agency
Marnie Duthie-Holt
Medi-For Forest Health Consulting

The Exotic Forest Insect Guidebook is intended to reduce the number of invasive alien species (IAS) that enter Canada.

The guidebook includes descriptions of insects, the damage they cause, the host trees they attack, and their geographic distribution. Most of the species identified in this guide could pose a serious risk to Canada's forests if introduced, but some have already been established in Canada.

This publication was originally published in 2004 by the Canadian Food Inspection Agency.

This publication is also available in hard copy and on CD. To order a copy, call 1-800-442-2342.

ACKNOWLEDGMENTS

We are very grateful to Rob Favrin, Louise Dumouchel, Bruce Gill, David Holden, Erhard Dobesberger, John Garland and Doreen Watler, CFIA, Leland Humble, Edward Hurley and Wayne MacKay, Canadian Forest Service, John Borden, Simon Fraser University, Jerry Carlson, New York State Lands and Forests and Ron Kimoto for reviewing various sections of the text. As well, preliminary text contributions were made by Scott Holt, Medi-For Forest Health Consulting and Jennifer Burleigh and Alex Gustafsson, Phero Tech Inc.

French translation was reviewed by Louise Dumouchel, Jean-Guy Champagne, Steve Cote, Marcel Dawson, Mélanie Mecteau, and Jacqueline Van Acker.

Various literature searches were conducted by Patricia Madaire and Greg Eldridge, Agriculture and Agri-Food Canada. Design review was conducted by Rob Favrin, Jacqueline Van Acker, Kurt Sauder, Nancy Kummen, Jerry Dowding, Ches Caister, Kara Soares and Ken Marchant, CFIA.

Financial assistance for the production of this guidebook was provided by the Professional and Technical Development Section, CFIA.

Troy Kimoto and Marnie Duthie-Holt

Introduction

Trees and forested areas are invaluable resources as they provide ecological, economic, spiritual and social benefits to all within Canada.

Human activities impact the surrounding environment by altering the structure and dynamics of ecosystems. The rate and extent of global trade and human migration have increased dramatically over the years. This expansion has increased the probability that organisms can be accidentally moved to and become established in areas outside of their natural range.

Most organisms fail to survive when introduced into a new environment or moved over long distances. Sometimes the conditions are suitable for an introduced organism to survive, find an appropriate food source and successfully reproduce in its new environment. Once established, their population levels may increase rapidly because the predators, parasites and diseases which attack them in their native range are not usually present in the new environment.

Canadian forests have been dynamically evolving since the last ice age (~10, 000 years ago) in response to fire, climate and indigenous insects and diseases. When exotic forest pests become established, trees are abruptly exposed to a new invasive species and may not have the mechanisms to defend themselves. In conjunction with the absence of population-limiting factors, the establishment of introduced forest pests may lead to either localized or large scale tree mortality that can impact private residences, municipalities, industries and forest ecosystems. Recently, the Emerald Ash Borer (Agrilus planipennis), a metallic woodborer native to China, has become established in North America where it is causing extensive mortality to green and white ash trees and threatens to severely limit the distribution of these species. However, in this insect's native range such damage has rarely been observed.

The Canadian Food Inspection Agency (CFIA) has a mandate, under the federal Plant Protection Act, to protect Canada's plant resource base against the introduction and spread of quarantine pests according to standards outlined in the International Plant Protection Convention. The CFIA does this by developing import, export and domestic regulatory policies and associated inspection, surveillance and eradication programs.

PATHWAYS OF INTRODUCTION

In terms of introduced organisms, pathways can be defined as means by which organisms are moved to new environments. Various plant health policies have identified that the greatest risks of introducing forest insects are generally associated with the importation and domestic movement of:

  • Wood packaging material
  • Shipping containers
  • Nursery stock
  • Firewood
  • Raw logs with bark
  • Christmas trees
  • Personal effects

Wood packaging material can be one of the most important pathways for the introduction of exotic forest insects because it is often used to ship a wide variety of consignments (e.g. steel products, granite, break bulk, glass, machinery, vehicles, consumer products, etc.).

The risk posed by wood packaging varies with wood quality and degree of finishing. The higher the grade and degree of finishing, the less likely the possibility of infestation.

In the past, many exotic plant pests have been intercepted on loose wood dunnage, pallets, crating or other wood packaging made from low grade material from various origins. North America has recently agreed to begin the implementation of a new International Plant Protection Convention standard (ISPM #15) that will regulate the movement of international wood packaging.

Cities and urbanized areas have higher probabilities of receiving exotic forest pests because of the large volume of goods that are imported into those areas. Urban trees and forested areas are often exposed to poor growing conditions due to soil compaction, air pollution, mechanical damage, etc. The combination of these factors increases their vulnerability to exotic forest pests.

CFIA forest pest surveillance programs target the routes of these pathways and high risk locations (e.g. international ports or terminals, industrial zones, landfills and storage sites, nurseries, etc.). For example, high risk consignments within transport containers are inspected at major ports before they are permitted to enter Canada. However, only a small proportion of these containers are inspected upon entry and therefore, a large volume of uninspected wood packaging material is transported to urban and rural centres throughout Canada. As it is a tremendous undertaking to monitor the introduction of forest pests in a country the size of Canada, it is important to have many additional "eyes" that are on the lookout for exotic organisms.

OBJECTIVES

This book is designed for public and private sector Canadians who work in the areas of tree health and arboriculture. This book focuses more on insect descriptions, host tree preferences, damage symptoms and geographic distribution rather than insect biology in order to increase the probability of finding exotic pests during tree health assessments. A key issue in the eradication of quarantine insects is discovering and identifying populations while they are still at low and controllable levels. Hopefully this book will serve as an early detection tool.

This book is intended to help detect exotic forest insects and should be used in conjunction with indigenous pest field guides. However, the information within this book will not transform the reader into an expert in insect identification. Some exotic insects, especially bark beetles, may resemble indigenous or naturalized insects. Some of the damage caused by exotic and indigenous forest insects may also be very similar (e.g. red needles). Therefore, suspect specimens need to be examined by professional entomologists for conclusive identification. Most of the insects included in this book could pose a serious threat if they became established in Canada. However, there are a few that have already become established and are being eradicated and/or regulated. The insects within this book do not represent a complete list of exotic forest insects which could invade Canada. There are a large number of non-indigenous insects throughout temperate forest regions in the world and only a very small portion of these has been included.

HOW TO USE THIS BOOK

BOOK FORMAT

Descriptions of insects in this book are organized by guilds, which represents similarities in their biology and the part of a tree in which they breed. Bark beetles are small insects that usually feed beneath the bark on phloem. Woodborers are a diverse assemblage of round and flatheaded wood borers, wood wasps, weevils and other insects that feed within the wood. Defoliators are primarily moths, the larvae of which feed on foliage or needles. Within this guidebook, these guilds are colour coded for convenient referencing. The insects are also arranged alphabetically within each guild and each family.

For many exotic insects scientific information may be difficult to obtain. Some insects have not been extensively studied in their native range. Therefore, there is some variation in the amount of information presented for each insect.

For each insect, information is arranged into 6 categories:

  • Identification
  • Host trees
  • Location of infestation within the tree
  • Host condition
  • Distribution
  • Signs and symptoms

Identification briefly describes some of the key anatomical features that distinguish one insect from another.

Host trees indicates which trees, by genus, are known hosts of an insect.

Location of infestation within the tree describes the parts (roots, root collar, bole, branches, etc.) and tissues (foliage, phloem, sapwood, heartwood, etc.) that are attacked by the various life stages of the insect.

Host condition outlines the health status, age and size of trees that are attacked.

Distribution lists the countries or regions in which the insect is either native or has been introduced.

Signs and symptoms describes the characteristics that are indicative of insect attack (signs such as colour of frass, exit hole size and shape, egg gallery shape, etc.) and outlines a tree's response to attack by the insect (symptoms such as resinosis, fading foliage, thinning crown, etc.). Literature cited within the text of this book is assigned a unique number. Citations can be looked up in the Reference section at the back of the book.

Two cross-reference indexes are provided. The first index can help determine which insects will attack specific parts of a given tree. The second index indicates which tree genera are known hosts of specific insects.

Wherever possible, non-scientific language is used throughout this book to describe the insects. However, in some instances entomological terminology is used. A glossary is located at the end of the guidebook to define these terms.

DETECTING EXOTIC FOREST INSECTS

Detecting newly introduced forest insects can be very difficult because the population may be localized and still at very low densities. Furthermore, the signs and symptoms may be masked by other factors. However, there are specific clues that can be used to increase the likelihood of detection. General symptoms of decline in coniferous trees are a thin crown, stunted leader (i.e. top) and a chlorotic or reddening crown. In broad-leaved trees, epicormic shoots, wilted leaves, thin crown and pre-mature foliage colour change are common indications of decline. Although these symptoms characterize many other types of forest health stress factors (e.g. drought, root disease, hail damage, insects, mammals, salt damage, sun scald), they are also the most obvious external indicators of exotic insects. How to Use this Book

Obtaining a "search image" for these symptoms is an initial step in locating potentially infested trees. As many exotic forest insects tend to breed in stressed trees, it is important that inspectors and surveyors check all obviously declining trees. This is particularly important in urban areas where trees often grow in sub-optimal conditions and are subjected to many stress factors.

In order to find infested trees, the surveyor must scan the entire length of a tree. Vigilance and general observation for declining trees is most beneficial. Scanning trees while walking through parks, sparsely treed industrial areas, woodlots, fencerows, riparian corridors or other wooded areas is critical in quickly locating and identifying an early attack.

General symptoms of decline should draw attention to a tree or a group of trees. The next step is to determine the causal agent. Familiarity with indigenous or naturalized biotic and abiotic forest health factors as well as local site conditions will greatly enhance the likelihood of an accurate assessment. External signs of insect activity include the presence of larvae or adults, frass (within bark cracks or crevices, on understory leaves, at the base of the tree, etc.), exit holes, entrance holes, pitch tubes along the bole, resinosis, gouting, oviposition niches, defoliation (partial or complete) and silk webbing. Internal signs such as egg and larval galleries, tunnels within twigs or branches, pupal chambers and the presence of various insect life stages can be uncovered by removing portions of the outer and inner bark with an axe or knife. Permission from the landowner is always required for more invasive investigations.

If the cause of tree decline seems suspicious, contact your local municipal or city forester, provincial ministry of natural resources entomologist/pathologist or professional arborist. Record pertinent information (street address or geographical coordinates, tree species affected, observable signs and symptoms, etc.) and if possible, collect a specimen (preferably adults) as these will assist professionals in evaluating the situation.

SAMPLE SPECIMEN SUBMISSION

This guidebook should assist in recognizing the presence of introduced forest insects but it can not replace the years of specialized training required to correctly identify insect species. There are many anatomical characteristics that require microscopic examination by specialists. The "Identification" section within the text of this guidebook only provides a general description of an insect and does not contain enough information to allow the reader to dependably identify an insect to the species level. If all other sources (e.g. local forest health specialists, native forest insect guidebooks, etc.) are unable to provide a definitive identification of a forest pest, please contact a Plant Health specialist at your local Canadian Food Inspection Agency office(www.inspection.gc.ca).

Troy Kimoto
Survey Biologist
Canadian Food Inspection Agency


Top of Page
Important Notices