Life Cycle of the Gypsy Moth
Female larvae usually go through an additional sixth instar growth stage, therefore feeding longer and growing larger than the males. The female caterpillar often become more pale colored in the this stage but retains the red and blue spots and the yellow head. They often reach a lenght of two and a half inches (60 mm).
Both male and female eventually turn into pupa where they metamorphise into adults. The first part of this process is when they spin a rough web of silk, as shown here, just enough to hold them to the tree. The body contracts and the skin is eventually shed.
Sometimes late in the gypsy moth season a virus infects the caterpillars and kills large numbers of them. This virus (
Lymantria dispar
Nucleopolyhedrosis Virus, shortened to NPV) is widely distributed but does not always activate into an epidemic for the gypsy moth.
Gypsy moths infected with NPV die in a distintive posture; head down, usually hanging from the middle legs (pro-legs). At first the body cavity liquifies but over time the caterpillar desicates, as this photo shows.