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What do these worms look like?
What color, size(inches), any information will help.
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Are the worms fuzzy? Perhaps they look like the image below? Where are these ferns growing?
Do any of the worms have markings or legs on them?
These are caterpillars and will turn into butterflies and moths later on. Click here for more information. Early control recommendations include: Dipel which will leave a white residue on foliage, but very effective in eliminating caterpillars and is safe to use. Mavrik and Talstar are both very effective for caterpillars (worms) and act primarily as repellents.
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