Phenology is the study of recurring biological events, especially natural plant and animal rhythms that occur earlier or later in the year in response to seasonal and climatic changes in the environment. Newly-constructed bags with fresh plant bits are effectively camouflaged in among the needles and are hard to find.Ī second method for predicting when new caterpillars will be on the trees is to use phenology. Also, bags are made of silk and bits of plant foliage. This will take time and diligence as the newly emerged caterpillars and their bags are quite small. One method for finding the best time to treat is to frequently and thoroughly inspect trees that were infested last year. That's quite a range in time that gives us plenty of room for error (too early or too late). So we want to spray just at the time the eggs are hatching and the small larvae appear.Īccording to various references, the bagworm eggs that spent the winter inside the silk pods hanging on the trees from last year's infestation should start to hatch in late May or early to mid-June. Insecticide control becomes less effective as the season progresses and the larvae increase in size. It's a logical concern, but please wait a little while longer.īagworm insecticides such as Bacillus thuringiensis, spinosad, Sevin, permethrin or bifenthrin will be ineffective and a waste of time if they are applied too early (just like they were a complete waste of effort when they were applied too late last summer!). There has been considerable interest and worry in the southern half of Iowa this spring as homeowners and property managers start thinking ahead to whether the bagworm caterpillars will defoliate their spruce, cedar or arborvitae trees again this summer as badly as they did last.
0 kommentar(er)
