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Erannis tiliaria

Linden looper caterpillar. Photo: Steven Katovich, Bugwood.
Scientific Name: 
Erannis tiliaria
Common Name: 
Linden Looper
Growing Degree Days (GDD's): 
192–363, Base 50F, March 1st Start Date (Source: Bob Childs, UMass Extension and Cornell Cooperative Extension.)
Host Plant(s) Common Name (Scientific Name): 
American hornbeam (Carpinus caroliniana)
Apple (Malus spp.) *Preferred host.
Ash (Fraxinus spp.)
Basswood (Tilia spp.)
Birch (Betula spp.) *Preferred host. (First instar larvae.)
Blueberry (Vaccinium spp.)
Cherry (Prunus spp.)
Elm (Ulmus spp.) *Preferred host.
Hickory (Carya spp.) *Preferred host.
Linden (Tilia spp.) *Preferred host.
Maple (Acer spp.) 
Oak (Quercus spp.) *Preferred host.
Poplar (Populus spp.) *Preferred host. (First instar larvae.)
Rose (Rosa spp.)
Serviceberry (Amelanchier spp.)
Willow (Salix spp.)
Witch hazel (Hamamelis virginiana) *Preferred host.
Insect Description: 

Periodically, the population of the linden looper rises to the extent that deciduous trees such as linden, apple, birch, elm, hickory, maple, and oak are defoliated. This native insect is found in the northern half of the United States and parts of Canada. Their populations can also overlap with the cankerworms. Adult female moths lay their eggs in clusters of 3-4 under loose bark on the trunk and larger limbs of its hosts. (One female was dissected and her abdomen contained 583 eggs (average of 300 eggs per female; Schoene, 1916).) Eggs are pale yellow in color when first laid, but turn to lead-gray prior to hatch. Eggs hatch at bud break (late-April to mid-May) and the caterpillars spend approximately one month feeding on host plant foliage. Early instar caterpillars can spin a silken thread and disperse using the wind by ballooning. These geometrid caterpillars have 2 pairs of prolegs and move in an inch-worm motion. Early instar larvae feed during the day, and older caterpillars may feed overnight. Fully grown caterpillars can be up to 3.5 cm in length, with yellow sides and a band along the back which varies in color between individuals. The back may possess up to 10 dark pinstripes, with yellow or brown in between. The underside of the caterpillar is chalk-colored. The head capsule of the caterpillar is usually a pale orange-brown. The spiracles (breathing openings; seen along the yellow stripes on the sides) are ringed in black. 4-6 instars are reported for the caterpillar stage, with 4 being reported as typical in Massachusetts populations. Eventually, caterpillars crawl to the ground beneath their host where they burrow 2-6 inches into the soil. This is where pupation occurs. Caterpillars finish feeding by mid-June and are typically in the soil by July. The greatest numbers of pupae are reported from the soil beneath leaf litter beneath trees and shrubs. From October to December, typically after the first frost, the adult moths emerge and wingless females lay their eggs. Female moths have two rows of large black spots along their back and are approximately 13 mm in length. Like other wingless female moths, they crawl up their host plants to lay their eggs. Males fly at night, and are sometimes attracted to outdoor lights in large numbers, and may be especially noticeable in vehicle headlights. Adult moths are called linden looper moths - however some literature refers to them also as "winter moth". In Massachusetts, however, that common name refers to Operopthera brumata. Caterpillars of the linden looper may also be called "lime tree looper" by some, however that common name may refer to another non-native species (Hybernia defoliaria) found in Europe. Linden loopers are a "boom and bust" species. In most years, their populations are present in low numbers. Occasionally, population outbreaks lead to localized defoliation. Johnson and Lyon (1991) and Wagner et. al (2001) note that the overwintering life stage is the egg in this species, however Wagner (2005) states that the pupa overwinters in an earthen cell - this may refer to the behavior of this insect in the part of its range found in Canada, where most of the adult emergence is reported in the spring (Britton, 1932). 

Note: A 1965 Master's thesis by Chih-Chung Liu, "Preliminary study of the life history and behavior of the linden looper, Erannis tiliaria (Harr.) (Lepidoptera: Geometridae)." is a great resource for more information about historical outbreaks of this native species, as well as its biology and natural enemies, in Massachusetts. 

Damage to Host: 

Typically, this insect is present in low-level populations that do not attract any attention. However, simultaneous outbreaks of this species have occurred in parts of the Northeast and Canada in previous years. In the spring of 1912, large numbers of caterpillars were reported in New York. In 1925, an outbreak that caused defoliation in New York, Massachusetts, and Connecticut occurred. In 1960, the population of this insect began to build leading to an outbreak in 1962 in Massachusetts, Connecticut, and Vermont. According to the literature, this outbreak continued to expand through 1963 and collapsed again in 1964 (Liu, 1965). This caterpillar consumes all of the leaf except the midrib and petiole, however initial (early) damage may look like elongated holes chewed in the leaves. Heaviest feeding may occur at the top of the host plant, or on lower, exposed branches. During outbreaks, serious defoliation of deciduous forests and understory shrubs may occur. 


Tree bands deployed in the fall may be used to monitor for egg-laying females during population outbreaks of this insect. Look for early ballooning or feeding caterpillars on host trees and shrubs beginning in late-April to mid-May. Luckily, this species typically exists in low, non-damaging populations - so monitoring yearly may not be necessary unless a regional outbreak is anticipated or occurring.

Cultural Management: 

Tree bands may help slightly reduce the amount of egg-laying by female moths on host plants, however the exact level of population reduction by using this technique is unknown for this species. If it is anything similar to winter moth (Operophtera brumata), female moths may still be able to get beyond the bands to lay their eggs, in which case this technique is more useful for monitoring than it is for management. Raking leaf litter away from the base of host plants during an outbreak may help make the site less desirable for pupation of the insect.

Natural Enemies & Biological Control: 

A virus that kills the older larvae of the linden looper was reported in 1961 and identified as a nuclear polyhedrosis virus. In 1963 it was reported to kill 8% of the linden looper population in Telham, MA. Caterpillars impacted by the virus become inactive, stop feeding, and change color before they eventually droop from leaves, branches, or host plant trunks. Virus killed caterpillars become black and shriveled. Unidentified bacteria and fungi are also noted in virus-killed caterpillar populations from the 1960's. Also in 1963, four species of tachinid fly parasitoids were identified from linden looper larvae - Phorocera (Pseudotachinomyia) slossonaePhryxe pecosensis, Ictericophyto spp., and Oswaldia spp.. Each were identified as ectoparasites (those that lay their eggs on the outside of the host) of 3rd and 4th instar linden looper larvae. Each leave the host when it is time to pupate and create puparia in the soil. Over 80% mortality of the linden looper population may be caused by these tachinid parasitoids. Predators were also reported - with a species of ground beetle, Calosoma frigidum, also feeding on 3rd and 4th instar larvae. Chickadees and spiders were also reported as predators of the adult male moths (Liu, 1965).

Chemical Management: 

Abamectin (NL)

Acephate (NL)

Acetamiprid (L)

Azadirachtin (NL)

Bacillus thuringiensis subsp. aizawai (L)

Bacillus thuringiensis subsp. kurstaki (NL)

Beauveria bassiana (NL)

Bifenthrin (NL)

Chlorantraniliprole (NL)

Chlorpyrifos (N)

Chromobacterium subtsugae (NL)

Cyantraniliprole (NL)

Deltamethrin (L)

Emamectin benzoate (L)

Flonicamid+cyclaniliprole (N)

Gamma-cyhalothrin (L)

Horticultural oil (L)

Indoxacarb (L)

Insecticidal soap (NL)

Neem oil (NL)

Pyrethrin+sulfur (NL)

Spinetoram+sulfoxaflor (N)

Spinosad (NL)

Tebufenozide (NL)


When used in a nursery setting, chlorpyrifos is for quarantine use only.

Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), acetamiprid (injection), azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), cyantraniliprole (soil drench, soil injection), emamectin benzoate (injection), and neem oil (soil drench).

Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.

Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.

Read and follow all label instructions for safety and proper use. If this guide contradicts language on the label, follow the most up-to-date instructions on the product label. Always confirm that the site you wish to treat and the pest you wish to manage are on the label before using any pesticide. Read the full disclaimer. Active ingredients labeled "L" indicate some products containing the active ingredient are labeled for landscape uses on trees or shrubs. Active ingredients labeled "N" indicate some products containing the active ingredient are labeled for use in nurseries. Always confirm allowable uses on product labels. This active ingredient list is based on what was registered for use in Massachusetts at the time of publication. This information changes rapidly and may not be up to date. If you are viewing this information from another state, check with your local Extension Service and State Pesticide Program for local uses and regulations. Active ingredient lists were last updated: January 2024. To check current product registrations in Massachusetts, please visit: .