Fattest Animal


This cutworm moth (Family Noctuidae) is the fattest animal in the world. In just two summer months of feasting on flower nectar, the migratory moths balloon from 20% to 80% body fat (1). Storing this much energy has a price though – no romance. Migratory moths put reproduction on hold to save up energy for their journey.

Thanks to all that fat, cutworm moths are a major food item for grizzly bears in the summer (2).

It got me wondering: These moths delay reproduction so they can migrate, but putting on fat makes them more delicious. Why not just stay put and make some babies instead? Since their migration is basically east-west, major temperature/seasonal shifts don’t require the move*. Local plants (food) don’t require the move either **. Parasites might. Army cutworm moths are highly parasitized. Moths with parasites stay in the Rocky Mountains longer, growing larger and fatter. So the bears may do the whole population of moths a favor by culling those with parasites.

* Altitude is a factor in temperature and season. But if moths stayed near the mountains, they could stay put moving up and down in altitude without flying a few hundred miles to and from the plains.

** Larvae eat a wide range of leaves and stems. Adults suck up flower nectar. So a large number of larvae may reduce some food for the adults.

  1. Kevan, PG and DM Kendall. 1997. Liquid Assets for Fat Bankers: Summer Nectarivory by Migratory Moth in the Rocky Mountains, Colorado, U.S.A. Arctic and Alpine Research 29(4):478-482
  2. French, SP, MG French and RR Knight. 1992. Bears: Their Biology and Management. p 389.

Ecology of “The Force”


As Obi-Wan Kenobi explained, The Force is “an energy field created by all living things. It surrounds us and penetrates us; it binds the galaxy together.” These sage words constituted my first exposure to an ecological idea: Energy.

Jedi are no fools. Every drop of energy we use (and rely upon) comes from outer space. Solar energy reacts with carbon dioxide and water inside those wondrous Earthly chemists, plants, to build the most amazing molecule of all – sugar. Sugars combine to form building blocks of plant bodies and, when eaten by an animal, these components break apart to release energy. We use this energy to power our bodies.

Life forms even store energy by combining sugars into fats or oils. The oil saved up by an unfathomable number of plants, buried millions of years ago, power our machines today. We call these ancient plant oils “fossil fuels.” Breaking apart those molecules releases the energy (and carbon dioxide) made long, long ago.

In a sense, that energy does surround and penetrate us; it flows through us.

May the Fourth (be with you) is Star Wars Day. Enjoy it by appreciating the energy of all living things that bind us together.