It’s not easy to be a pine tree in the western United States these days. Weather fluctuations are creating infestation paradises for a variety of insects (Douglas-fir tussock moth, sawfly infestation), including throughout Colorado.
The most recent challenge that has targeted pine forests of El Paso and Elbert counties, Franktown, Elizabeth and parts of Parker is the sawfly, a brown wasp whose larvae feast on ponderosa and other pine needles after hatching. According to Denver Post report, the sawfly infestation reached epidemic levels this month (July 2015). To date, experts have not pinpointed the environmental conditions that resulted in this year’s infestation.
Each pine needle can be home to about 20 sawfly eggs. Sawflies lay their eggs in the fall during what’s known as their flight period. Insects follow an internal calendar, but most sawfly flight periods take place in September and October. The eggs overwinter and if weather conditions are mild, virtually all of the eggs could hatch in the spring. A crowded pine needle nursery could result in a starvation death for about half of the larvae, but epidemic numbers still survive.
Larvae mostly enjoy both existing growth on ponderosa and other pines and complete defoliation of trees is being seen in affected areas. Defoliated trees are a fire hazard and should be addressed by property owners.
According to the Colorado State Forest Service, the best time to address a sawfly infestation is when the eggs begin to hatch in June. However, inspection of pines during and after the sawfly’s flight period in the fall can identify signs of existing eggs that will hatch in the spring. Natural controls include diseases, parasitic wasps, and other predators.
Contact SprayTech, Colorado commercial and residential tree-spraying specialists, at 720-248-0000, for inspection of pine trees on your property and to discuss sawfly treatment options.
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