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A
special thanks to Klaus Bolte of the CFS for his superb, leading edge
photography of the insects on this year’s National Forest Week Poster
 Biodiversity:
All things big and small
Eastern
spruce budworm, Choristoneura fumiferana (Clemens)
The spruce budworm is the most destructive forest insect pest in North
America east of the Rocky mountains. This native defoliator (needle eater)
of balsam fir and spruce trees may strip more than 30 million hectares
of trees during an epidemic. In Ontario alone, from 1982-1987, spruce
budworm damage caused growth loss of 1.6 million cubic metres and the
death of trees amounting to 7.2 million cubic metres of wood. Seven cyclical
outbreaks, each lasting 25-30 years, are thought to have occurred in Eastern
Canada over the past 250 years.
Life
cycle 
The eastern spruce budworm has four life stages, egg, larva (or caterpillar),
pupa (resting stage between the larval and adult stage), and adult.
The larva sheds its skin (moults) several times as it grows;
the period between moults is called an instar.
Female moths lay masses of about 20 eggs on needles of host trees in
mid-July to early August. The eggs hatch in about eight to 12 days;
the first instar larvae don't feed but disperse and seek protected places
to spend winter, often under bark scales. After spinning a hibernaculum
(a light silk web to hibernate in), the larva moults to the second instar
and does not develop further until spring. The next spring, larvae disperse
and start feeding; newly opened flowers on balsam fir trees are the
preferred food. If those are not available, the larvae feed under the
bud caps of expanding shoots, or they tunnel inside needles (usually
only one per larva). When they moult to the fourth instar in early June,
the larvae feed on new foliage until the sixth instar, then stop feeding,
and form a place to pupate among needles webbed together. Adults emerge
in early to mid July, mate, and lay eggs.
Recognizing
the Eastern spruce budworm
The adult eastern spruce budworm is a moth with a wingspan of about
2 cm. It is usually grayish with dark brown markings but some are brown
or reddish with gray markings. Spruce budworm eggs are light green and
measure about 1 mm long by 0.2 mm wide. The first larval instar, about
2 mm long, is yellowish green with light- to medium-brown head. The
second instar is yellow with a dark brown or black head. During the
next four instars, the body of the larva changes from a pale yellow
to a dark brown with light-coloured spots along the back. In the sixth
instar, the larva is about 2.5 cm long and the head is dark brown or
shiny black. The pupa is pale green at first, and later changes to reddish
brown; it is marked with dark bands and spots.
Damage
Infested fir stands take on a reddish colour in the summer due to the
dead needles being stuck to the tree by strands of silk. In the fall
these needles are carried off by wind or rain and the stands then appear
more gray. Prolonged outbreaks of spruce budworm cause severe branch
and top kill and ultimately lead to tree death.
Two
close relatives to the eastern spruce budworm are the western spruce
budworm, C. occidentalis (Freeman) on Douglas fir and the Jack
pine budworm, C. pinus pinus (Freeman), on Jack pine. These insects
are also serious pests in Canadian coniferous forests.
Gypsy
moth, Lymantria dispar (Linnaeus)
The gypsy moth is one of the most notorious defoliators (leaf eaters)
of broad-leaf trees in Canada. It first arrived in Medford, Massachusetts,
in 1869 and made its Canadian debut in 1924, in southern Quebec. Another
invasion of the gypsy moth occurred in New Brunswick in 1936. Both these
invasions eventually died out, but a third one, near Montreal in 1959,
did not and the gypsy moth has continued to spread from there. It can
now be found throughout the St. Lawrence-Great Lakes forest region of
Quebec and Ontario, as far west and north as Lake Superior, and east to
Nova Scotia and New Brunswick. Isolated infestations of the European strain
had recurred in British Columbia but were wiped out. An Asian strain originating
from Russian ports was found in 1991 but was also wiped out.
Life
cycle 
The gypsy moth lifecycle has four stages: egg, larva (or caterpillar),
pupa (resting stage between the larval and adult), and adult. The larva
sheds its skin (moults) several times as it grows; the period between
moults is called an instar. Adult moths appear from about mid-July to
August. They mate immediately and each female produces 100-800 eggs
in a flattened, hair-covered mass that can be found attached to various
objects. The eggs overwinter and hatch into caterpillars the following
spring as the leaves of the host trees are unfolding. The caterpillars
feed mostly at night and rest during the day, often under loose bark
or in ground litter. They reach maturity in late June and spin a cocoon
for themselves in which they pupate. The pupal period lasts about 10
days and the adult moth then emerges.
Recognizing the Gypsy moth
Female gypsy moths are large, with a wingspan about 6 cm, and heavy-bodied.
Male gypsy moths are smaller (3-4 cm wingspan) and darker in colour.
The caterpillar is about 4 to 6 cm long when fully grown. It is dark
grey, marked on the back with blue and red spots and is covered with
tufts of long hairs.
Damage
Gypsy moth caterpillars generally feed on broad-leaf species such as
oaks, willows, aspens, birches, and other, less favourable species;
older caterpillars will also eat conifer needles. The larvae cause most
of the defoliation in the last 2 weeks of feeding. During severe outbreaks,
all trees and shrubs in an infested area are completely stripped of
their leaves or needles. Although trees are not readily killed, even
by repeated attacks, there is a considerable loss of wood production.
From 1981-1986, more than one million hectares of trees were moderately
or severely damaged in Ontario.
Infested areas may be identified by the presence of egg masses on trunks
and branches.
Forest tent caterpillar, Malacosoma disstria
(Hübner)
The forest tent caterpillar is a native defoliator (leaf eater) widespread
in North America. The forest tent caterpillar prefers trembling aspen,
but also attacks other broad-leaf trees such as poplar, willow, birch,
and cherry. Outbreaks that last two to six years may occur every 10 to
15 years and millions of hectares may be defoliated.
Life
cycle
The forest tent caterpillar lifecycle has four stages: egg, larva (caterpillar),
pupa (resting stage between the larval and adult stage), and adult.
The larva sheds its skin (moults) several times as it grows. The period
between moults is called an instar.
The moths appear in July and females lay egg masses around twigs. Each
mass contains about 150-250 eggs and is covered with a frothy brown
substance, produced by the female, which hardens to protect them. Eggs
overwinter and hatch in spring when the leaves start to unfold. Young
larvae spin silk mats on the larger branches and trunks upon which the
older larvae rest when they are not feeding. Large larvae tend to wander
and may feed on various unusual hosts, such as conifers. The larvae
develop completely in about 6 weeks. When full grown, they spin cocoons
for pupation in folded leaves, under loose bark, or in ground litter.
The pupal stage lasts about 2 weeks. Forest tent caterpillars produce
only one generation a year.
Recognizing
the Forest tent caterpillar
Adult moths have a wingspan of 2.5-3.7 cm and are tan coloured, with
two dark parallel lines crossing the middle of the forewing. The caterpillars
are bluish to brown with somewhat diamond-shaped white spots on the
middle of the back of each segment, and two thin, broken, yellow lines
along each side. The pupa is reddish brown in a loose cocoon commonly
formed inside rolled leaves.
Damage
Infested trees are identified by the presence of groups of caterpillars
on the foliage and trunks. Egg bands on the twigs can easily be seen
before the tree leaves come out in spring.
Forest
tent caterpillar outbreaks do not usually last more than three to four
years. Although complete defoliation may occur, even for many years
in a row, typically this does not kill the tree. However, branches are
killed and woody growth is lost. An unfortunate result is that vacationers
tend to avoid using recreational areas that have large numbers of affected
trees.
Mountain
pine beetle, Dendroctonus ponderosae (Hopkins)
The mountain pine beetle is the most destructive insect pest in western
North America. It occurs throughout the pine forests of British Columbia
and Alberta, and south to northern Mexico. Several species of pines are
attacked by this beetle.
Life
cycle
The mountain pine beetle's one-year life cycle has four life stages,
egg, larva, pupa (resting stage between the larval and adult stage),
and adult. The young adult beetles emerge, spread out and attack new
host trees over a short period, usually in mid to late July.
Eggs are laid in a gallery (tunnel dug by the beetle) bored in the pine
phloem (tubes of cells that carry sap from the leaves to the rest of
the tree) by a female. The eggs hatch into small larvae that dig short
feeding tunnels at right angles to the egg gallery; these tunnels vary
in length and are on the inner bark surface. A larva sheds it skin (moults)
several times as it grows. The period between moults is called an instar.
Larvae then hibernate and resume feeding the following year. Full grown
larvae pupate in oval pupal cells under the bark and eventually transform
into adults. The mature adults bore through the outer bark and fly to
attack new host trees. At high elevations or at the northern limit of
the beetle's range a partial or complete 2-year cycle may occur.
Recognizing
the Mountain pine beetle
Adult mountain pine beetles are rather stout, black cylindrical beetles
that measure from 4 to 7.5 mm long. Their antennae are small, elbowed
and have a flattened end. Larvae of the mountain pine beetle are white,
curved and legless and resemble grains of rice.
Damage
The damage caused by this insect is due to boring in the inner bark
by adults and feeding larvae. The adult females dig galleries mainly
in the inner bark. This cuts off the circulation of water and nutrients
and contributes to the death of the tree, especially when the galleries
encircle the trunks so that the tree is girdled. This girdling blocks
the downward movement of food from the leaves and causes the roots to
die. The tree tops then die because the dead roots can no longer absorb
and supply water to the other tree parts.
Adult mountain pine beetles also leave a trail of blue stain fungus
that kills the resin-producing tissues in attacked trees, contributing
to tree death. Each year millions of trees are killed by the mountain
pine beetle. An epidemic may last five to 10 years and could spread
over hundreds of thousands of hectares. Over the past 80 years, more
that 500 million trees have been killed by the mountain pine beetle
in British Columbia.
Asian
long-horned beetle, Anoplophora glabripennis (Motschulsky)
In 1997, Asian longhorn beetles (ALB) were intercepted at various locations
throughout North America. This beetle is native to Northeast Asia and
is a serious pest of hardwood trees in China. In British Columbia and
Ontario, the interceptions of the beetle have been associated with wood
packing material in shipments of metal pipe, and wooden spools used for
transporting cable or wire rope. There is no evidence that this species
is established in Canada, but the detection of this beetle at ports shows
a potential threat to Canadian forests. Depending on where you live, the
Asian longhorn beetle is known by many different names. For example, in
China it is known as the starry sky beetle.
Because
of an infestation of ALB discovered in Brooklyn and Amityville, NY, in
1996, over 1000 trees were removed. So far over $1 million has been spent
in the United States in an effort to wipe out this species.
It
is particularly important that we keep the Asian longhorn beetle out of
Canadian forests because this beetle attacks and kills healthy trees.
Many hardwood species would be at risk, including poplar, red alder, big
leaf maple, willow, bitter cherry and various other trees. The climates
of some southern portions of Canada make these areas more likely to sustain
this insect.
Life
cycle
In its native range, the Asian longhorn beetle may have a one or two-year
life cycle. The four stages of the cycle are egg, larva, pupa (resting
stage between the larval and adult stage) and adult. This beetle has
the ability to overwinter as an egg, larva or pupa.
Beetle eggs hatch in 11 days into small worm-like larvae. The larva
sheds its skin (moults) several times as it grows.The period between
two moults is called an instar. Early instars larvae feed on the phloem
(tubes of cells that carry sap through the tree). Late 4th- instar larvae
move into the xylem (tubes of cells that carry water and nutrients from
the soil up to the leaves) and in early spring mature larvae change
into the pupal stage in the wood. Adult beetles begin emerging in May
and the population peaks in early July. Adults fly for 2-3 days to feed
and mate, then females make grooves in host tree branches to lay eggs.
Recognizing the Asian-longhorn beetle
Asian longhorn beetles have large bodies that range from 20-35 mm long
and 7-12 mm wide. The first pair of wings are hard, black and shiny
and can bear up to 20 white dots. These wings cover and protect the
second pair, which is used for flying. Asian longhorn beetles'antennae
are longer than their bodies and are made up of 11 segments. Each segment
is black with a whitish-blue ring at the base and the insect's legs
are black, tinged with a whitish-blue colour.
Damage
Adults feed on the leaves and bark of trees and this causes considerable
damage. They prefer to attack the shoots of host trees, causing the
young shoots to wither and die. The female beetle chews round or lip-shaped
grooves on branches, where she lays her eggs. Young larvae feed in the
sappy, green inner bark and as a result, the bark becomes concave. Mature
larvae bore into the heartwood of the tree and create large, winding
galleries in the inner wood, eventually killing the tree. Emerging adults
chew their way out of the wood creating large, circular exit holes and
pushing out heavy, coarse wood fibres that fall to the ground. Infested
trees are also prone to attack from other insects and diseases. Yellowing
foliage and early leaf loss are other signs that the ALB is present.
The
increase of global trade and rapid transport of people and materials
require us to be more alert to both the import and export of pest-infested
wood products. The Canadian Forest Service requests your assistance
in reporting any suspected sightings of this beetle or its damage. To
report sightings or suspected damaged caused by ALB, contact the nearest
Canadian Forest Service (Natural Resources Canada) laboratory.
Brown Spruce longhorn beetle, Tetropium
fuscum (Fabricius)
The brown spruce longhorn beetle (BSLB) is found in and around Point Pleasant
Park, a 75-ha heritage park located in the Halifax Regional Municipality,
in Nova Scotia. The Halifax population is the first established one of
BSLB discovered in North America.
It is evident that BSLB has been present in Nova Scotia since at least
1990, when it was first collected in the park. Because the park is located
next to a major port, it is believed that imported wood packing material
provided the entry route for this pest. The insect has also been intercepted
at the ports of Montreal and Vancouver, where it was found in solid wood
packaging.
This
woodboring insect is native to northern and central Europe and western
Siberia where it attacks dead and dying trees. In Halifax, however, the
beetle also attacks living, apparently healthy red spruce, which is the
most plentiful species in the park. Other trees attacked by the BSLB include
black spruce, white spruce and Norway spruce.
Each of the North American spruces is a new host association for this
pest. Fir, pine, larch, and occasionally hardwoods are attacked across
its native range in Europe and Asia. Canada's climate and the widespread
distribution of spruce trees make it likely that this species will thrive
here, if it escapes into the boreal forest.
Life
cycle
In its new Canadian environment, BSLB can complete its life cycle in
one year. The four stages of the cycle are egg, larva, pupa (resting
stage between the larval and adult stage) and adult. Eggs are usually
laid singly or in pairs, are well concealed under bark scales, and are
securely attached. The larva feeds initially in the inner, living bark
and later scores (makes cuts or lines on) the sapwood. It spends winters
in the larval stage, but during the summer months all four life stages
may be present in the host. The beetles bore networks of wide, winding
feeding tunnels, up to 6 mm across, and fill them with tightly packed,
fine-grained excrement and short wood fibres. It spends winters in the
larval stage, but during the summer months all four life stages may
be present in the host. At maturity the larvae dig a shallow, oval-shaped
pupation chamber in the sapwood or inner bark. The larvae pupate in
spring after a period of winter dormancy. Adults begin to emerge in
spring and continue to over a six to eight (6-8 ) week period. As soon
as the beetles appear in spring, mating and host selection begins.
Recognizing the Brown spruce longhorn beetle
Brown spruce longhorn beetles are generally quite small, measuring 0.8
to 1.8 cm in length with red-brown antennae that run about half the
body length. A beetle's head and thorax are dark brown to black and
its body is slightly flattened, dark tan, brown, or reddish brown, with
a lighter coloured band across the shoulder portion of the wing.
Damage
Much of the tree's cambium (where growth occurs) can be destroyed by
the feeding tunnels constructed by the larvae. The transport of nutrients
is disrupted by larval feeding in the phloem. Trees can be re-infested
in subsequent years. Although the entire trunk can be attacked, the
lower portions appear to be most heavily infested. Eventually, when
the trunk is girdled, the tree dies.
What
to look for
Attacked trees produce excessive resin that is noticeable down the length
of the trunk. Infested trees may quickly begin yellowing, browning,
and losing needles from portions of the crown. After the tree is killed,
the remaining foliage turns reddish brown. Trees infested for more than
one year have round to oval adult exit holes, averaging 4 mm in diameter.
Response
The Canadian Food Inspection Agency (CFIA) has identified BSLB as a
pest of plant quarantine significance under the terms of the Plant Protection
Act. In an effort to eradicate this quarantine pest in Halifax, Nova
Scotia, a multi-agency and multi-disciplinary task force was formed
in the spring of 2000. The Canadian Forest Service is working closely
with the task force to provide scientific support and research information.
Removal of infested spruce trees is ongoing in an attempt to eliminate
this pest from North America.
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