{"id":11293,"date":"2021-02-25T15:23:07","date_gmt":"2021-02-25T20:23:07","guid":{"rendered":"https:\/\/extension.umaine.edu\/home-and-garden-ipm\/?page_id=11293"},"modified":"2021-03-03T11:25:45","modified_gmt":"2021-03-03T16:25:45","slug":"hemlock-looper","status":"publish","type":"page","link":"https:\/\/extension.umaine.edu\/home-and-garden-ipm\/fact-sheets\/common-name-listing\/hemlock-looper\/","title":{"rendered":"Hemlock Looper"},"content":{"rendered":"
\"An<\/a>
Eastern Hemlock Looper (Lambdina fiscellaria<\/i>) (resting by a porch light in Stetson, Maine; 9\/15\/2019)<\/figcaption><\/figure>\n

The Hemlock Looper<\/strong>, Lambdina<\/i> fiscellaria<\/i> (Guen\u00e9e), is a native North American moth belonging to the family Geometridae, the second largest family in the order Lepidoptera.\u00a0 The family accounts for many serious agricultural and forest pests, the hemlock looper being no exception. Its larvae are a pest of balsam fir, hemlock, sugar maple, white birch and occasionally spruce and larch trees.\u00a0 In Maine, it has been recorded on every native conifer and many deciduous trees, as well as some shrubs and ornamentals, but the Maine Forest Service lists balsam fir, hemlock and white spruce as being most at risk from hemlock looper.<\/p>\n

\"An<\/a>
Eastern Hemlock Looper (Lambdina fiscellaria<\/i>) (Farmington, Maine; 9\/8\/2020) (Photo courtesy of Hannah A.)<\/figcaption><\/figure>\n

There are three distinct and regional subspecies of hemlock looper (albeit with some debate): the Eastern Hemlock Looper (<\/em>Lambdina fiscellaria fiscellaria), <\/em>the Western Hemlock Looper (Lambdina <\/i>fiscellaria <\/i>lugubrosia), <\/i>and the Western Oak Looper (Lambdina<\/i> fiscellaria<\/i> somniaria).<\/i>\u00a0 The Eastern Hemlock Looper occurs–as its name suggests–in eastern North America, encompassing the Atlantic provinces of Canada west to Alberta, and stretching in the US from Maine to Georgia and west to Wisconsin.\u00a0 As one moves more northward in its range, balsam fir is increasingly preferred, whereas hemlock is its preferred host as one travels farther south.<\/p>\n

Life Cycle and Damage<\/h2>\n

Eggs:<\/strong> Hemlock looper has a single generation per year and overwinters in the egg stage.\u00a0 Eggs are only about 1 mm in length, are laid from late August to October, and are deposited singly or in groups of two or three in a variety of locations including branches, bark, and even the forest floor amongst lichen and moss.\u00a0 Eggs begin hatching in late May and\/or early June and continue hatching through about the middle of June.<\/p>\n

Larvae and Tree Damage:<\/strong> Larvae are present from late May\/early June into August and progress through four to five instars (typically five<\/i> but in Newfoundland there are only four instar stages).\u00a0 The loopers (inchworms) feed initially on new foliage but soon they switch over to old foliage and will only feed on new foliage again when the old foliage is depleted.\u00a0 They are very wasteful feeders, nipping only a small part of a needle before moving on to another [the photo on page 2 of this<\/em> USDA Forest Service Pest Alert<\/strong><\/a> illustrates the ‘nipping’ or ‘notching’ feeding behavior<\/em>].\u00a0 Damaged needles dry out, turn reddish-brown, and later die.\u00a0 Needles are often clipped off, forming a mat below the tree.\u00a0 High populations of the larvae can remove nearly all of the tree’s needles in only a single season!\u00a0 Defoliation is often heaviest in the undergrowth because larvae tend to drop off or fall from their position if they are disturbed.\u00a0 At maturity, larvae reach about 1.5″ in length.\u00a0 By late July, mature larvae begin dropping to the ground to pupate in whatever protected places they can find.\u00a0 In areas with heavy infestations, the trees will be covered with silken strands that the larvae spin and use as ropes when they drop from the branches.\u00a0 Hemlock trees may die after only a single year of severe defoliation.\u00a0 Fir trees may die after one or two years of severe defoliation.\u00a0 Deciduous trees, by contrast, rarely suffer significant damage from loopers.\u00a0 Hemlocks, firs and white spruces that happen to lose more than 70% of their needles from hemlock looper usually suffer long-term effects that sometimes will kill the trees eventually or at least kill individual branches or the tops of the trees.\u00a0 If more than 90% of the needles are lost, significant mortality is seen.\u00a0 The same is true if the trees are defoliated for several seasons<\/p>\n

Pupae:<\/strong>\u00a0 The pupae vary in appearance but generally have brown and green coloration as well as dark spots. There is no cocoon formed around the pupa.\u00a0 Pupae are most likely to be found in cracks and crevices on the bole of the tree, in decayed stumps, in spaces in and around moss and lichens, and under any type of debris found on the ground.\u00a0 The pupal stage lasts approximately 22 days.<\/p>\n

Adults\/Moths:\u00a0<\/strong> Hemlock looper moths begin emerging around the end of August, with emergence continuing until the middle of September.\u00a0 Males often are the first to emerge, by an average of about four days.\u00a0 The moths are small, with a wingspan of about 1.25″ in length, and are colored tan to gray-brown but with a wide variability within the species in the intensity of the colors.\u00a0 When at rest, the moths lay very flat in the shape of a broad wedge.\u00a0 They are active starting in the late afternoon and continuing through the night, from late summer through the fall.\u00a0 During heavy outbreaks, one can find large numbers of moths resting and mating on the tree trunks and on the underlying vegetation.\u00a0 Male hemlock looper moths live for about ten days whereas females live for about 14 days.\u00a0 Each mated female can deposit up to 150 eggs, and since looper moths are weak flyers and consequently don’t travel very far away, populations can be heavy in a localized area, giving rise to very large numbers of eggs per tree.<\/p>\n

Outbreak Dynamics<\/h2>\n

The population dynamics of hemlock looper are poorly understood.\u00a0 During outbreaks, the populations tend to crash after two to three years regardless of weather conditions.\u00a0 Rarely does an outbreak last more than three or four years. Occasionally, however, an outbreak may last six or more years!\u00a0 Infestations are noted for their rapid escalation and sudden collapse, but are usually heavy and long enough<\/i>\u2014before they collapse\u2014to cause very high levels of defoliation and tree mortality.\u00a0 Outbreaks usually begin as small, often widely-scattered infestations which gradually increase in size and distribution each year (if conditions allow) and eventually begin to overlap to form a single large, irregular outbreak area.\u00a0 The reason for the crash of hemlock looper outbreaks is most likely the work of natural enemies (e.g.<\/em> viruses, fungi, parasitoids and predators), but the right combination of weather conditions may also be a primary factor.\u00a0 They do not do well during unusually cold and wet summers, and heavy rains during the moth flight period can interfere with mating opportunities.<\/p>\n

Newfoundland <\/strong>has had many significant hemlock looper outbreaks in the past, with the period between outbreaks highly variable:<\/p>\n