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Identification & Biology
Trees Gypsy Moths Like
How Gypsy Moths Harm Trees
Where Gypsy Moths Are
Gypsy Moth Management
Slow The Spread (USFS and Indiana DNR)
For Homeowners
Impact on Homeowners
Harm to Trees
How Gypsy Moths Move
Your Tree’s Health
Clean Up Your Yard
Destroy Egg Masses
Control of Caterpillars
Insecticides for Caterpillars
Control of Pupae
Control of Adults
Gypsy Moth Activity Calendar
For Professionals
Quarantine Information
History of Gypsy Moths
Asian vs. European Gypsy Moth
Gypsy Moth Management for Homeowners

How Gypsy Moths Harm Trees

The caterpillar poplulation explodes.
(Jodie Ellis, Purdue University)

Voracious Feeders

Like most caterpillars, gypsy moth caterpillars are virtual eating machines that consume as much as they can, as quickly as they can. Their feeding period lasts from 7 to 10 weeks. Unfortunately for homeowners, gypsy moth caterpillars can feed on over 500 types of trees and plants.

Gypsy moth caterpillars feeding on leaves.
(Vince Burkle, Indiana IDNR)

Gypsy moths can exist at low population levels for years, but approximately every 10 years their populations explode. This occurs for several reasons (favorable weather or a lack of predators or diseases, for example). This rapid swelling of population size is called an outbreak.

Gypsy moth caterpillars collected during an outbreak.
(Jodie Ellis, Purdue University)


During large outbreaks, trees are stripped of their leaves within a few days by hungry caterpillars. Although most trees will re-grow new leaves before summer ends, the energy used to accomplish regrowth stresses the tree and drains its reserves.

Aftermath of a gypsy moth outbreak leaving
trees bear of foliage.
(Vince Burkle, Indiana IDNR)

Weakened trees and shrubs are more susceptible to attack by opportunistic diseases and organisms such as armillaria root rot and two-lined chestnut borers. In addition, the tree’s growth rate is slowed, negatively affecting its chances for long-term survival.

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