Few moths make someone stop in awe or pull out a camera as often as the sphinx moths of our province. These nocturnal moths can be drawn to lights where they can be mistaken for a bat or small bird by their size. Perhaps this is where the other name, hawk moth, comes from. I had a recent encounter with a few of the Big Poplar Sphinx, the biggest in our province between 10 -15 cm in length. Their fuzzy abdomens are about as thick as my little finger; the yellow fringed antennae looked like two ornamental feathers protruding above their big black eyes. Their multiple layers of brownish grey hues blend very well with the bark of trees, but if you pay close attention you might catch a glimpse of the pink and blue colours on parts of their hind wings. Many sphinx moths are pollinators who are looking for nectar, but the big poplar sphinx do not eat as adults. They are just looking for an opportunity to mate and lay their two hundred eggs.

Most of the sphinx moths will be flying from July till the start of August. The eggs of the Big Poplar Sphinx are laid on poplar leaves and will become “super” big green caterpillars. August is the perfect time to keep an eye out for these immense 14-gram larvae. They are also known as horntails because they are light green with a few white embellishing stripes on their body and a harmless spike protruding from their back end. To predators, this “horned tail” looks formidable, but even with it only about a quarter of the caterpillars born survive. The best place to start your hunt is in groves of aspen or poplars like the balsams, and the cottonwoods of the prairies.

They start their caterpillar lives eating the eggshells they were born in. Their appetite for poplar leaves is insatiable for four weeks. They spend this time chewing and resting, relying on their green camouflage and obscure body shape to evade predators. They grow so much that they shed their skin several times during this period. When they have eaten enough they descend from the leaves of the poplars onto the ground, taking on a purplish hue. Here they burrow into a cell in the soil. With one final shed of their skin, they become pupae.

The Big Poplar Sphinx pupa is amazingly resilient and will stay underground all winter until June slowly transforming through the process of metamorphosis. When this process is complete they will emerge from the pupa case, dry their immense wings, and take to the skies, once again filling our nights with a sense of wonder at how an insect living in Canada could ever grow so big. If you are fortunate enough to encounter these beautiful neighbours, please refrain from touching them, particularly on their sensitive wings to ensure their survival. However, if you are lucky, a sphinx moth may grant you the honour of landing on you.