Scientific Name: (Operophtera brumata)
The winter moth belongs to the family Geometridae in the Genus Operophtera. It is also among a few Lepidopterans whose adults become active during early winter or late fall in the temperate areas. Usually, such adults rely on internal heat to regulate their body temperature as they conserve and generate heat during a flight in cold temperatures. Winter moths are the invasive pests in North America, and their prevalence is more widespread on conifers and deciduous trees that cause severe defoliation when present in excess. Moreover, orchard plants that fell prey to winter moths include apples, pears, plums, and cherries. The winter moth is the most damaging pest that could restrain a tree from setting fruit when infested and cause significant damages to the growers of apples, especially.
Origin and Distribution
The winter moth has lineages both in Europe and Western Asia. Especially in Turkey and Egypt, and along the borders of Eastern Europe, and Western Asia. The Winter Moth become invasive in North America in the early nineties, which later spread to Nova Scotia and British Columbia. Additionally, they were reported from Eastern States of the US in the late '90s. Presently, the winter moth is a proven pest in Massachusetts, Maine, Rhode Island, New Hampshire, Oregon, and Washington State Besides, Southeastern Connecticut and eastern Long Island in the US.
Winter Moth- Identification
The forewing color of a male moth varies from greyish-yellow to fawn-brown or sometimes slightly reddish with tints. The pattern's color often varies from banded dark brown to blurry. The fringe of the winter moth is distinctive yellow. The rare wings are light or yellow-grey. The antennae are short with fine hairs. The female moth has rudimentary wings but, she is flightless and, her color often remains brownish grey. Female rudimentary wings have dark bands, and the color varies from brown to grey. A male & female moth usually measures up to 1 centimeter in length. A mature larva can have ¾ of an inch’s size.
Winter Moth- Lifecycle
Winter moth caterpillar emerges after egg hatching in early spring near terminal buds when the daytime temperature remains above 50°F for several days. Newly hatched larvae feed on the terminal buds, where buds are also their hiding places. Then they can move to plants foliage to spend up to 6 weeks of their growth stage. Besides feeding on the foliage of the targeted plants, they can also build wind-blown silk strands with the neighboring trees. In summer, a green color larva could slide down to the shade under the trees and prepare for pupation. Pupation occurs in the soil in early to mid-summer. Usually, adults emerge from their hidings in early to late fall. Since the female of a winter moth has only rudimentary wings and can't afford flying, she releases a sex pheromone to attract the males of the same species. After successful mating, the female usually lays eggs ranging from 150 to 350 in number. The eggs are typically small, and the crevices of the tree bark protect them from predators. Since the pupation period is typically long in a winter moth, they could be prone to several predators.
Symptoms and Types of Damages
Primarily, Winter moth caterpillars could potentially damage apple flower buds. They enter the flower buds from the green tips by pinching a hole that destroys the flower which, can't turn into mature fruit. Their feeding continues throughout the summer on apples but, they could also feed similarly on the opened flower clusters of plums, cherries, and pears. Usually, the early foliar and the tender shoots remain their target, and sometimes they could also continue feeding on small developing fruitlets. If a fruit survives the injury, it could reflect a concave or flat fruit surface and sometimes splits in the fruit. It could defoliate a targeted tree, completely depriving you of healthy fruit in the coming season.
Where Do the Winter Moth come from?
Winter moths emerge from the eggs after the environmental conditions suit them, during early or late spring. Do monitor daytime temperatures if you want to be vigilant about their presence in your garden. If the temperature continuously exceeds 50°F for several days, it’s the time to show presence in your garden.
How to Prevent Winter Moth?
How to Control Winter Moth?
Biological Control
Monterey-Bacillus Thuringiensis, Worm & Caterpillar Killer 
Monterey-Bacillus thuringiensis has 98.35% Lepidopteran active toxins with over six million viable spores per milligram of solution. BT is a soil-living, Gram-positive bacteria and one of the best biological insecticides the world over. This Bacterium naturally exists inside the gut of caterpillars of both butterflies and moths besides in an organic-rich environment especially, animal feces and surfaces of the leaves. The mode of action is Cry Proteins production that ruptures the gut of the host insect leading to their death. Bacillus thuringiensis is also abbreviated as BT which is an active organism behind BT Cotton, BT Corn, and other genetically modified crops. BT is also listed in OMRI and approved for organic gardening without having side effects on the fruits or vegetables.
- INSECT KILLER - This pest control is designed for use on caterpillars and worm type insects, such as cabbage looper, bagworm, gypsy moth, fall cankerworm, elm spanworm and many more.
- FOLIAGE PROTECTOR - This insecticide is designed for use on a variety of plants including broccoli, celery, cabbage, turnip greens, mustard greens, cauliflower, melons, lettuce, tomatoes, shade trees, ornamentals and many more.
- SAFE FOR EARTHWORMS & BEES - When used as directed, Monterey B.t. has no effect on birds, earthworms, or beneficial insects such as honeybees or ladybugs.
Add one ounce of Monterey-BT concentrate in one gallon of water and spray on the foliage of the fruit trees when winter worms are during the initial stages of their development.
Organic Control
Natural Guard Spinosad Soap
This Spinosad Liquid Soap contains 0.940% Potassium Salts of Fatty Acids and 0.005% of Spinosad in the form of Spinosyn A, and Spinosyn D which, is a good combination for killing Caterpillars of winter moths besides killing aphids, leaf miners, whiteflies, and Thrips when the target is an organic formulation. It has no residual effects on edibles and can be applied just before harvesting. However, a strong product dose can kill honey bees and other pollinators that often visit your garden space. It’s truly quick in killing that starts within minutes after application.
- Specially formulated to protect your vegetables, crops, lawns and outdoor ornamental plants against foliage-feeding insects
- Uses a powerful combination of two active ingredients, it effectively controls spider mites and kills pest on contact
- Effective against powdery mildew when it is sprayed directly on contact, plus a complete coverage for total control
Spinosad Soap comes in ready-to-use chemistry, connects a garden hose with the pack to spray on the foliage.
Garden Safe-Insect Killer
Garden Safe-Insect Killer is 85% DE (Diatomaceous Earth) that is best applied when the caterpillars or larva are seen for the first time in a garden. DE is the best organic remedy that kills insects while coming in contact with their bodies. The mode of action is dehydration and killing of starvation. It can be applied in a fruit garden on cervices of the tree bark and other potential hiding places of larva, caterpillars, or other insect pests which are not seen flying in your garden. DE is OMRI listed, has no residual effects, and safe for the environment, as well.
- FOR ORGANIC GARDENING: Diatomaceous earth-based formula is good for organic gardening
- FOR USE OUTDOORS: Apply a thin layer of the fine/powdery granules to plants and on the soil around plants
- KILLS BY CONTACT: Kills listed insects by contact. Dust insects directly, if possible
Thinly dust it around hiding places or spread on the surfaces of the leaves to target any insects pest you would like to kill. Repeat application if necessary.
Ortho-Tree & Shrub Fruit Tree Spray
This product is exceptional in killing whatever pest damages your fruits on a tree or a shrub. It's ideal chemistry for the apples, pear, and plums that kills eggs, larva, and adults of winter moths when applied at the first appearance and then repeated biweekly. It contains 70% clarified hydrophobic extract of Neem oil and 0.25% Pyrethrins besides 2.5% Piperonyl Butoxide that enhances the effects of both insecticides. It’s a low toxicity product with minimum residual effects on edible plants and can be sprayed on the day of harvest. Pyrethrins when mixed with Piperonyl Butoxide don't remain organic however, the toxicity levels are still low and can be used for long-maturing fruit crops.
- Controls insects, diseases and mites
- Kills insect stages, including eggs, larvae and adult. Controls aphids, mealybugs, mites, scale, whiteflies, beetles and other listed insects
- Can be used up to day of harvest
Add one ounce of product concentrate in one gallon of water and spray on the foliage using a hand-held sprayer.
Chemical Control
BioAdvanced- Fruit, Citrus & Vegetable Insect Control for Edible Gardening
Its systemic insecticide is 0.235% Imidacloprid and suits well to fruit and vegetable crops due to its low percentage of the active ingredient. This product applies twice a year: once in the spring or then in the fall. It's not meant for foliar spraying instead, it mixes with water and is poured directly onto plant roots. The drench type of application makes it safer for the pollinators and the bees.
- SPECIAL FORMULA FOR EDIBLE GARDENING: Fruit, Citrus & Vegetable Insect Control is specially formulated for use on over 100 listed fruits, vegetables, and citrus plants to kill listed insects and prevent new infestations
- LISTED INSECT KILLER: Kills Aphids, Asian Citrus Psyllid, Asiatic Garden Beetle Grubs, Avocado Lacebug, Blackfly, Citrus Leafminer, European Chafer Grubs, Japanese Beetle*, Japanese Beetle Grubs, Leafhoppers, and other listed pests. *Adults feeding on foliage
- SEASON-LONG PROTECTION: One easy application provides season-long insect protection without the need for spraying; Prevents new infestations for up to 2 months
32-ounces of the product concentrate can treat 640-square feet area of fruit plants.
Check out our other guides on common garden bugs.