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Identification & Biology
Trees Gypsy Moths Like
How Gypsy Moths Harm Trees
Where Gypsy Moths Are
Gypsy Moth Management
History of Gypsy Moths
Asian vs. European Gypsy Moth
Identification And Biology Of The Gypsy Moth In Indiana

Caterpillars - Late April Through Early June

New hatchlings begin to leave the egg mass.
(Paul A. Mistretta, USDA Forest Service,

After resting in the egg mass through winter, eggs begin to hatch in late April.

Thousands of tiny black-headed caterpillars about 1/8th of an inch long climb to tree tops where they either begin to feed on foliage or drift in the wind from silk strands to other trees.

Early instar caterpillars.
(Terry McGovern - USDA APHIS PPQ)

After newly hatched caterpillars begin to
feed, they rapidly grow and change appearance.

As they grow, they become largely black
with irregularly shaped yellow marks visible
on the upper body surface.

All caterpillars have one purpose in life
- they need to feed!

Gypsy moth caterpillars are quite colorful
with their red and blue bumps. Mature
caterpillars reach up to 2 inches long.
(John Obermeyer, Purdue University)

  • Older gypsy moth caterpillars develop distinct colored "bumps" on their backs; five pairs of blue bumps followed by 6 pairs of red bumps.

  • The mature caterpillars may reach up to 2 inches long.

  • Caterpillars feed on foliage from late April to early June. Each caterpillar consumes up to 11 square feet of foliage each over the course of its life.

  • Most feeding occurs at night to protect caterpillars from extreme heat and predation by birds during the day.

Feeding Caterpillars

Caterpillars feed on oak leaves.
(Vince Burkle, Indiana IDNR)

Caterpillars hiding in the folds of the burlap.
(Jodie Ellis, Purdue University)

Defoliation of an oak tree during an outbreak.
(John Obermeyer, Purdue University)

Defoliation during an outbreak.
(T. McGovern - USDA APHIS PPQ)

The Aftermath of Heavy Feeding by Caterpillars

A defoliated oak forest in summer after gypsy moth outbreak. (USDA APHIS PPQ)

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