What physical change might an observer notice in a caterpillar immediately before it undergoes a molt?

Answer

Becoming sluggish or appearing slightly dull in color

Before a molt occurs, the caterpillar often becomes sluggish or appears slightly dull in color as it prepares to shed the tight outer layer.

What physical change might an observer notice in a caterpillar immediately before it undergoes a molt?

#Videos

Caterpillar Shedding - YouTube

skinlarvacaterpillarSwallowtailmolt