Life Cycle of the Cecropia moth, Hyalophora cecropia

The Cecropia moth is a member of the family Saturniidae that includes many of North America's largest moths.  Only the Atlas moth is bigger.  The Cecropia ranges across the United States from the East Coast to the Rocky Mountains.  It is "univoltine", meaning only one generation is produced per year.  The pupae who have spent the winter months in their cocoons emerge in late Spring or early summer, and live for only a few days - enough time to find mates and for the females to lay eggs before they die.

The larvae - caterpillars - feed on a variety of host plants including cherry, maple, lilac and others.  They are voracious eaters and molt four times as the get larger and larger.  The hatchlings are so small as to be hard to see and emerge from eggs about 2 mm in diameter.  But after shedding their skins over a period of about six weeks, the mature caterpillars are bigger than a man's middle finger.


Distinguishing features:

  • About 1-1.5 mm in diameter
  • Whitish or pale beige in color with darker spots
  • Attached to leaves or twigs of host plants
  • Laid in clutches of two to ten or more eggs, in rows or clumps.

Hatchlings - 1st instar caterpillars

Distinguishing features:

  • All black integument and scoli.  As caterpillars approach molt, they start to look puffy and more brownish as their skin stretches.
  • Group feeding occurs with several individuals feeding alongside each other on the same leaf.

First molt and 2nd instar caterpillars

Distinguishing features:

  • Body yellow with black spots.
  • All scoli black.

Second molt to 3rd instar caterpillars

Distinguishing features:

  • Body yellow with black spots in longitudinal rows between scoli.
  • Large orange scoli on segments two and three, each bearing eight spikes - seven pointing roughly horizontally around circumference near crown, one pointing vertically.
  • One row of blue scoli superior laterally, one row of black scoli inferior laterally.
  • Spiracles white.
  • Pads of prolegs tinged with blue.

Third molt from 3rd to 4th instar

Distinguishing features

  • Body green laterally blending to more bluish dorsally.  Black spots between rows of scoli.
  • Four bright red scoli, one pair on second body segment, one pair on third body segment.
  • Pairs of yellow scoli dorsally on fourth to eight segments.
  • Two rows of blue scoli laterally.

Fourth and final molt as a caterpillar - 5th instar

Caterpillar Development - 1st to 5th instar

1st instar caterpillar, about 3 days old.

1st instar caterpillar, just before 1st molt to 2nd instar - about 9 days old.

2nd instar caterpillar, about 12 days old.

2nd instar caterpillar just before molting, about 16 days old.

3rd instar caterpillar, just after molting from 2nd instar.

3rd instar caterpillar - typical appearance.

4th instar

Just molted to 4th instar - about 5 weeks after hatching.

4th instar caterpillar - typical appearance.

5th instar - final caterpillar stage

5th instar caterpillar - about 7 weeks after hatching.

5th instar caterpillar begins constructing cocoon - about 8 weeks after hatching.


Adult Cecropia moth,  Hyalophora cecropia  - one of North America's largest moths, with a wingspan of around eight inches.

Adult Cecropia moth, Hyalophora cecropia - one of North America's largest moths, with a wingspan of around eight inches.