The Tent Caterpillar Truth
As the weather warmed earlier this spring, we started spending more time outdoors, enjoying our parks and gardens, admiring the flowers and watching them grow. But amongst the blossoms and the fruit, you may have noticed something else in the trees that is a much less welcome sight: Tents. Growing around the tips of tree branches, alive with rapidly growing larvae we would soon see dropping from the treetops on silken strands, and on the move on sidewalks, walls and patio railings.
They’re living things we love to hate: Tent Caterpillars. Considered a pest, a nuisance, a destructive intruder we have a duty to eradicate. Some years they experience a population boom and seem to be everywhere, growing out of control. Then within just a few weeks we reach late summer and almost overnight they seem to just disappear, forgotten until next year. But how much do we really know about these little misunderstood creatures?
The Truth
But are they really that bad? True, caterpillars cause huge tree defoliation, but they don’t actually harm the tree trunk or root system. Tent caterpillars rely on the trees for the survival of their species into the next year, it would serve them no benefit to kill or make them sick. Healthy trees can re-leaf later in the season with tougher leaves that are less appetizing to predators. The amount of leaves falling this time of year are the proof of how many were growing through the summer months.
Western tent caterpillars build their cocoon around August and only spend a few weeks in it before emerging as the adult moth. They only live for a few more weeks, during which time their most important purpose is to mate and lay their eggs. The moths are much less noticeable then the caterpillars which is why we tend to forget about them. Moths reach the end of their life cycle in early fall, and die off soon after egg laying.
Tent caterpillars are a native species, meaning they are part of the native ecosystem. While not always evident to people trying to raise non-native plants – for instance roses, hydrangeas and rhododendrons – believed to be “at risk” by these perceived pests, it is important to remember that every native species plays an important part in the survival of the ecosystem. Western tent caterpillars serve their role, and the best thing humans can do is leave them and their predators alone so the ecosystem can continue to thrive for years to come.
Written by Darcy Harnadek, HAT volunteer.
References
Tent Caterpillars - Climate, Forests and Woodlands
Tent Caterpillars, what are they? - Government of Canada
Tent caterpillar season in Greater Victoria sees gardeners fight for their foliage - Victoria News
Outbreak of tent caterpillars creepy but harmless for your trees - Victoria News