is the larva doing — and why?
its Shed Exoskeleton
This monarch larva just shed its exoskeleton and is now eating the
remaining portion, called the exuvia. Like all insects,
a monarch must shed its exoskeleton at various stages to make room
for growth. (Each stage of growth is called an instar.
The process of shedding is called molting.)
Eat the Exuvia?
The most likely reason for eating the exuvia is to recycle the nurtients
it contains, especially hard-to-get nutrients like nitrogen. Dr.
Alex Mira studied this behavior in cockroaches. He found that animals
raised on low-protein diets ate the exuvia most often. Females also
ate the exuvia more than males, probably because of the need for
nitrogen in egg-production. (Female monarchs are known to get nitrogen
from males during mating, in a packet called the spermatophore.)
is a building block for proteins and genetic material, so it is
essential for life. Nitrogen is abundant in the earth's atmosphere
but is often a scarce resource in the food web.
© Bud Hensley
exuvia contains valuable nutrients. It is made of protein chains
and chitin. (Yum, yum!)