Instruct: Given a question, retrieve relevant passages that answer the question.
Query: How many eggs does the eastern spruce budworm lay?
Female moths lay one brood per season, and eggs are laid over several days. The number of eggs per egg mass varies from 1 to about 60, but there are 20 eggs on average per mass.[10] These masses are laid in 2 to 4 rows on conifer foliage, preferably balsam fir and spruce needles. Generally, females can lay 100 to 300 eggs in a lifetime but average approximately 200 eggs. These eggs hatch after around 10 days, but this period ranges from 8 to 12 days.[28][34] The spruce budworm oviposits on needles of host trees in late June or mid-July to early August.[35] Large numbers of egg masses are deposited on the peripheral shoots of the crown.[10]
The range of the eastern spruce budworm is the largest of all budworms and coincides with the range of its hosts: fir and spruce trees in eastern North America, primarily in Canada.[8][9] It includes the Boreal Forest as well as the Great Lakes-St. Lawrence, Northern, and Acadian forest regions.[10] This range extends westward to Alaska.[11] The spruce budworm is commonly found in boreal and sub-boreal forest regions, specifically those that consist of spruce-fir forests.[12]
It has been hypothesized by Serge Payette that the spruce-moss forest ecosystem was changed into the lichen woodland biome due to the initiation of two compounded strong disturbances: large fire and the appearance and attack of the spruce budworm.[76] The spruce budworm is a deadly insect to the spruce populations in the southern regions of the taiga. J.P. Jasinski confirmed this theory five years later stating “Their [lichen woodlands] persistence, along with their previous moss forest histories and current occurrence adjacent to closed moss forests, indicate that they are an alternative stable state to the spruce–moss forests”.[77]
The eastern spruce budworm is one of the most destructive insects of fir and spruce forests throughout Canada and the eastern United States.
The breeding habitat of this bird is the edges of coniferous woodland. Cape May warblers nest in dense foliage near the trunk of the tree, commonly a black spruce, and lay 4–9 eggs in a cup nest. This species can lay the largest clutch of any New World warbler, probably in response to increases in the numbers of spruce budworm during outbreaks.
This species is a favoured food of the Cape May warbler, which is therefore closely associated with its host plant, balsam fir. This bird, and the Tennessee and bay-breasted warblers, which also have a preference for budworm, lay more eggs and are more numerous in years of budworm abundance.
Traditionally, the eastern spruce budworm prefers balsam fir over white spruce.[17][18] However, one study showed contradicting evidence. In this study, Bichon sampled spruce budworm populations on branches from the upper mid-crowns of dominant or co-dominant balsam fir and white spruce. This was done at 20 randomly selected points in the Black Sturgeon Lake area near Thunder Bay, Ontario. The number of late-instar larvae captured in water traps was recorded throughout the dispersal period of the late instar larvae. The data indicated that white spruce canopies contained 2 to 3 times more spruce budworm than balsam fir canopies. A similar pattern was found in the understory. Water traps under white spruce trees captured more than 3 times as many larvae as did those under balsam fir trees for most of the dispersal period.[18]
Insectivorous birds are a common and major predator of the spruce budworm, mainly preying on the larvae and pupae. Examples of species include sparrows, thrushes, and overstory warblers. Bird distribution will change to reflect budworm density in the forests.[28] A 1989 study found that the highest populations of spruce budworm larvae and pupae occur in June and July. This coincides with the period when some species of birds require maximum food to feed their young. As a result, predation by birds helps control the growth of budworm predation.[9] Other major predators include various invertebrates, primarily spiders.[28]
Eastern spruce budworm moths are strong fliers and disperse in exodus in the evening. They can fly at elevations over 100 meters before going to a new site, which is typically only 50 to 100 kilometers downwind, but can sometimes be up to 450km away. After depositing some eggs at the first dispersion site, female moths may emigrate and lay eggs at multiple sites. Factors controlling budworm flight during dispersal include meteorological conditions and temperature. Moths will not disperse when the temperature is below 14°C or above 30°C. When the temperature drops below 14°C mid-flight, the moth will fold its wings and descend from the sky.[28]
Balsam fir is the most susceptible host to outbreaks of the spruce budworm. Annual defoliation of current-year growth for 5 to 8 years will kill the host tree.[16] Defoliation by the spruce budworm is most clearly reflected in the fir's radial growth. The population of mature balsam fir in a forest is greatly reduced by a combination of factors: its shorter lifespan and a great vulnerability to lethal budworm attacks.[19][20][21] The dietary preference for balsam fir over white spruce has the potential to alter the structure and composition of spruce-fir forests. Similarly, the next-generation stand of trees are influenced by the late instar larvae that disperse to the understory of the forest and feed on the regeneration of plants.[18] During a 1957 budworm outbreak in Quebec, balsam fir mortality was greater than 75% in stands in which no mortality was reported among the smaller component of white spruce.[22]
The eastern spruce budworm ("Choristoneura fumiferana") is a major pest of spruce trees in forests throughout Canada and the eastern United States. Two of the main host plants are black spruce and white spruce. Population levels oscillate, sometimes reaching extreme outbreak levels that can cause extreme defoliation of and damage to spruce trees. To reduce destruction, there are multiple methods of control in place, including pesticides.
Spruce are used as food plants by the larvae of some Lepidoptera (moth and butterfly) species, such as the eastern spruce budworm. They are also used by the larvae of gall adelgids ("Adelges" species).
In spruce-fir forests throughout Maine, the late-instar spruce budworm larvae is preyed on by eumenid wasps such as the A. adiabatus, and E. leucomelas. This predation is important in controlling populations of the spruce budworm in forest stands.[40]
The first recorded outbreak of the spruce budworm in the United States occurred in Maine in about 1807. Another outbreak followed in 1878. Since 1909 there have been waves of budworm outbreaks throughout the eastern United States and Canada. The states most often affected are Maine, New Hampshire, New York, Michigan, Minnesota, and Wisconsin. These outbreaks have resulted in the loss of millions of cords of spruce and fir. In 20th-century eastern Canada, the major outbreaks occurred in periods circa 1910–20, c. 1940–50, and c. 1970–80. These outbreaks impacted, respectively, 10, 25, and 57 million hectares of forest. Longer-term tree-ring studies suggest that spruce budworm outbreaks have been recurring approximately every three decades since the 16th century. Paleoecological studies suggest the spruce budworm has been breaking out in eastern North America for thousands of years.
The first recorded outbreak of the (eastern) spruce budworm in the United States occurred in Maine in about 1807, although it seems to have escaped notice of the entomologists until 1865. Another outbreak followed in 1878. Since 1909 there have been waves of budworm outbreaks throughout the eastern United States and Canada. Longer-term tree-ring studies suggest that spruce budworm outbreaks have been recurring approximately every three decades since the 16th century.
The moths will emerge from the pupae within 8 to 12 days, during mid-June to August. Adult spruce budworm are medium-sized (15mm in length) and dichromatic, exhibiting gray and rust colors.[12] The wings have silvery patches and are 21mm to 30mm in wingspan.[11] Peak activity occurs during the later afternoon and early evening.[37] After emerging, the adults will mate and lay eggs in July or August.[11][38]
For biological methods, birds are important in controlling populations of the eastern spruce budworm below outbreak levels, and the parasitic wasp "Trichogramma minutum" was investigated as a solution as well.
Their breeding habitats are coniferous woodlands. Bay-breasted warblers nest up in conifer trees, laying 3–5 eggs in a cup-shaped nest. Incubation is 12 days. More eggs are laid in spruce budworm years.
About 90 parasitoids have been collected from spruce budworm in eastern North America. In 1996, Henry found that the suite of parasitoids collected from spruce budworm in isolated white spruce plantations of southern Ontario differed from the usual suite of parasitoids found in the boreal forest.[41]
One dominant characteristic of the boreal is that much of it consists of large, even-aged stands, a uniformity that owes to a cycle of natural disturbances like forest fires, or outbreaks of pine beetle or spruce budworm that kill large tracts of forest with cyclical regularity. For example, the many stands of white spruce, black spruce, and balsam fir are vulnerable to the cyclical outbreaks of a species of the spruce budworm, the "Choristoneura fumiferana." Since the melting of the great ice sheet, the boreal forest has been through many cycles of natural death through fire, insect outbreaks and disease, followed by regeneration. Prior to European colonization of Canada and the application of modern firefighting equipment and techniques, the natural burn/regeneration cycle was less than 75 to 100 years, and it still is in many areas.
Long distance migration of the spruce budworm does occur as they can disperse across distances ranging from 20 to 450km. In northern Minnesota, spruce budworm moths emigrate to the east lakeshore of Lake Superior in Ontario, Canada, because of seasonal changes. Dispersal is influenced heavily by temperature as low temperatures can slow down both take off and arrival. Other factors include dispersal direction, precipitation, altitude, and wind flow. It is likely that mass exoduses of the C. fumiferana over long distances are a result of food shortage in the local area.[39]
In Atlantic Canada, the spruce budworm problem was noted as early as 1910.
Clemens originally named the eastern spruce budworm, C. fumiferana, in 1865, which was recognized as a Nearctic representative of the genus C<i data-parsoid='{"dsr":[3185,3201,2,2]}'>horistoneura.[2] At this time, the name applied to populations in a variety of geographic regions and biotopes. The C. pinus, a distinct form of the Choristoneura, was later established as a separate species. However, a large group of this genus in the western part of North America remained taxonomically undefined as the "western complex"[3] until T.N. Freeman established several new species in 1967.[4] Field collections of late instar larvae of Choristoneura populations were taken from a range of localities in a wide arc, from the Atlantic seaboard along the edge of the Laurentian Shield to the Mackenzie River area near the Arctic Ocean. From these collections, only points east of the Rocky Mountain foothills yielded C. fumiferana.[5] The two-year-cycle budworm C. biennis occurs only in the subalpine forest region,[6][7] with alpine fir and interior spruce as hosts. Budworm populations from Rocky Mountain regions south of the area of introgressive hybridization of spruce differ from C. biennis.[5] Other budworms are of little or no consequence with respect to spruces.
In locations such as New Brunswick, DDT pesticide was applied to over 3.6 million hectacres from 1952 to 1958 and 1960 to 1967. This use of chemical control effectively decreased the spruce mortality rate within this area and prevented significant economic impact. In fact, the government of New Brunswick formed Forest Protection Limited (FPL) as an agent with which "to fight the spruce budworm [which was] then threatening to destroy much of New Brunswick's fir-spruce forest".
Choristoneura fumiferana, the eastern spruce budworm, is a species of moth of the family Tortricidae. It is also commonly referred to as the spruce budworm. It is one of the most destructive native insects in the northern spruce and fir forests of the eastern United States and Canada. Its range is also the widest of all the budworm species. Eastern spruce budworm populations can experience significant oscillations. During outbreaks, populations grow to extremely high densities, compared to the relatively low levels that occur in between. These outbreaks are highly destructive and can cause both economic and ecological damage. As a result, methods of control are utilized. Several theories exist regarding these cyclical outbreaks: association with balsam fir maturation, catastrophe theory, dispersal from an epicenter, and oscillations synchronized by entrainment.