In Mahogany, a neighborhood in southeast Calgary, Samantha Tong was surprised when she observed what appeared to be moving tree bark, only to discover it was actually forest tent caterpillars covering the tree. Tong noticed several trees infested with these caterpillars near a playground, indicating a growing population in the area.
Similar spikes in caterpillar populations have been reported in municipalities like Red Deer, Olds, and Devon this spring. Forest tent caterpillars, native to Alberta, go through cyclical outbreaks roughly every decade, lasting two to three years. Ken Fry, an entomologist at Olds College, explained that these outbreaks are influenced by various factors such as weather conditions, tree health, and natural predators.
These caterpillars are known for their tree damage, mainly defoliating leaves. While healthy trees can recover from defoliation, stressed or diseased trees might struggle to rebound, making them susceptible to other pests like wood-boring beetles.
To address caterpillar infestations, non-chemical solutions like manual removal or using a biological pesticide called bacillus thuringiensis kurstaki (BTK) are recommended. Fry emphasized the importance of managing caterpillar populations to prevent prolonged defoliation, which can lead to tree damage and vulnerability.
During an outbreak season, forest tent caterpillar moths lay eggs in trees, leading to future infestations. Removing egg clusters can help mitigate the issue. Kath Smyth from the Calgary Horticultural Society highlighted the need for proactive measures to control caterpillar populations and prevent recurring infestations.
While forest tent caterpillars can pose risks to trees, they play a role in the natural ecosystem as a food source for predators and their feces serving as effective fertilizer. Understanding the broader ecological context can help appreciate the benefits these caterpillars bring despite their temporary nuisance.
Fry advised that trees struggling to recover from caterpillar damage may indicate underlying issues that need attention for tree health and care improvement. Monitoring and managing caterpillar populations can help maintain a balance in the ecosystem and promote healthier tree growth.
