Angustifolium gallii, 2015

Approximately one fifth of known Canadian insects (more than 2711 species) are represented in the Yukon.

Pictured here is Hyles gallii, a hawk moth, feeding on nectar at the base of a fireweed anther. On the leaves are two hawk moth caterpillars I found at the Takhini North disc golf course in autumn, 2014.

The darker caterpillar is getting ready to pupate. It will form a chrysalis and enter a period of suspended development (called diapause).

Some insect species can choose to enter diapause when food becomes scarce, others can pre-program their eggs with hormones that will cause their young to enter diapause or not, and, in the case of the hawk moth, some simply have no choice.

Yukon Mourning cloak butterflies and Blue azures also have no choice, but they overwinter as an adult butterfly and a caterpillar, respectively. The fact that diapause occurs at different stages of development between species shows that the phenomenon has evolved many times independently.