Third Instar
Body and head (x6)
| Color Pictures |
| 3rd and 4th Instar Comparison |
| 3rd Instar with molting head |
| 3rd Instar with detailed prolegs, truelegs |
| 3rd Instar |
Body length: 10 to 14 mm
Body width: 2 to 3.5 mm
Front tentacles: 1.7 mm
Back tentacles: 0.9 mm
Head capsule: 1.5 mm in diameter
Appearance: The black and yellow bands on the abdomen of a third instar larva are darker and more distinct than those of the second instar, but the bands on the thorax are still indistinct. The triangular patches behind the head are gone, and have become thin lines that extend below the spiracle. The yellow triangle on the head is larger, and the yellow stripes are more visable. The first set of thoracic legs are smaller than the other two, and is closer to the head.
Third instar larvae usually feed using a distinct cutting motion on leaf edges. Unlike first and second instar larvae, third (and later) instars respond to disturbance by dropping off the leaf and curling into a tight ball. Monarch biologist Fred Urquhart called this behavior "playing possum."
Egg | First instar | Second instar | Third instar | Fourth instar | Fifth instar