Bugs Leave White Fuzz on a Silver Maple Leaf

Woolly Alder Aphids

• Wooly alder aphids, or Paraprociphilus tessellatus, were named for the fluffy white wax on their abdomens, some of which can be left behind. They are grey to black, and require both alder and silver maples to complete their life cycles. They live in colonies on the leaves, twigs and bark of the trees. Though they seldom cause permanent damage, infested leaves will often shrivel and drop early in the season.

Scale

• Because scales are immobile, tiny and lack visible legs, they can appear to be inanimate substances left behind by other bugs. Various species of scale infest maples; some are flat -- and, indeed, scaly in appearance -- while others resemble white cotton. Scales feed by piercing leaves, stems or branches and sucking out the sappy fluid; this can eventually weaken or kill branches. Leaves can yellow and drop early in the season and trees with severe infections will be stunted and produce only small flowers and foliage.

Treating Woolly Alder Aphids and Scales

• Chemicals are not recommended as the first line of treatment for either woolly alder aphids or scale by experts at Clemson University's Cooperative Extension. Large trees can be impractical and expensive to treat and chemicals kill off the beneficial insects that keep their populations in check. Ladybugs naturally prey on both insects, while lacewings feed on aphids and parasitic wasps feed on scale. Gardening centers often sell populations of predatory insects like these that landscapers can release into infested trees.

Powdery Mildew

• Powdery mildew is a common plant fungal infection whose spores form white, fluffy areas on the tops of leaves -- which can resemble scale or other infestations. Make sure the white substance is a bug-related problem and not powdery mildew before attempting treatment, as they require different control methods. A common characteristic of powdery mildew that helps differentiate it from other problems is the small black specks that often accompany the white powder or fuzz. These specks help the fungus reproduce and survive colder temperatures. Powdery mildew can be treated with a wettable sulfur spray in severe or early season infections.