Insects diurnal

Woolly Alder Aphid

Prociphilus tessellatus

Often mistaken for a fungus or a dusting of snow, the Woolly Alder Aphid is one of the most charismatic insects in the backyard. These 'boogie-woogie' bugs create a spectacular shimmering display when they feel threatened, turning a simple tree branch into a pulsing sea of white fluff.

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Quick Identification

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Size

Individual aphids are 2–3 mm (0.08–0.12 inches), but colonies can cover several inches of a branch.

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Colors

Blue-black or gray bodies hidden beneath long, white, trailing waxy filaments that resemble cotton or wool.

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Key Features

Thick covering of white, waxy 'wool' filaments
Found in dense clusters on alder twigs or silver maple leaves
Distinctive 'pulsing' or 'dancing' motion when disturbed
Two-host lifecycle alternating between maple and alder

When You’ll See Them

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Activity pattern diurnal

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Peak hours Daylight hours, especially during calm, warm afternoons.

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Season May-June (on Maples) and July-October (on Alders).

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Diet Phloem sap extracted from the leaves of Silver Maples and the bark/twigs of Speckled or Smooth Alders.

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Habitat Wetlands, stream banks, and suburban yards where Silver Maples and Alders are present.

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Behavior

The Woolly Alder Aphid is best known for its 'boogie-woogie' behavior. When a predator or a large object (like a curious human) approaches the colony, the aphids lift their abdomens and pulse in unison, creating a shimmering white wave. This collective movement is thought to confuse predators like birds or lacewings. Despite their common name, they lead a complex double life, migrating between Silver Maples in the spring and Alders in the summer and fall.

These aphids are prolific 'honeydew' producers. As they suck sap from their host plants, they excrete a sugary liquid that coats the branches below. This often leads to the growth of black sooty mold, which, while unsightly, is part of the natural ecosystem. You’ll often see ants 'herding' these aphids, protecting them from predators in exchange for a taste of that sweet honeydew. Interestingly, they are the primary food source for the Harvester butterfly caterpillar, the only carnivorous butterfly larva in North America.

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Camera Tips

Capturing the Woolly Alder Aphid requires a shift in perspective compared to larger wildlife. Because these insects are tiny, your AI-powered camera or trail cam needs to be positioned for macro or extreme close-up shots. Look for 'snowy' patches on the underside of Silver Maple leaves in late spring or on the gray branches of Alders near water sources in the summer. Mount your camera just 6 to 12 inches away from the infested branch to capture the intricate details of their waxy filaments.

To trigger the most interesting footage—the famous 'dancing' behavior—you don't necessarily need a lure, but a slight physical vibration or a shadow passing over the colony often sets them off. If your camera has a high-speed video mode or time-lapse capability, use it. Time-lapse is particularly effective for showing how the colony expands across a branch over several days, while high-speed video is the only way to truly appreciate the rhythmic pulsing of the colony's defensive dance.

Lighting is your biggest challenge and best friend with this species. Their white waxy coating is highly reflective, which can 'blow out' your image in direct sunlight. Aim for a position where the branch is in dappled shade or use a diffuser to soften the light. Early morning or late afternoon provides the best 'rim lighting' that makes the woolly filaments glow against the dark bark of the alder. If you are using a trigger-based camera, ensure the sensitivity is high, as the motion of the aphids themselves is subtle, though the collective 'dance' is usually enough to wake a sensitive sensor.

Similar Species

Species that look similar or are commonly confused with Woolly Alder Aphid.

Beech Blight Aphid

Found only on Beech trees; their waxy filaments are typically shorter and they perform a more aggressive collective swaying motion.

Woolly Apple Aphid

Smaller and usually found on apple, pear, or hawthorn trees, often causing noticeable 'galls' or bumps on the twigs.

Frequently Asked Questions

Woolly Alder Aphid are active throughout the daylight hours. They are most easily observed and filmed during mid-day when the light is bright enough to see the detail of their white waxy filaments, though their 'dancing' behavior can be triggered at any time they feel threatened by a predator or vibration.

The best way to attract Woolly Alder Aphid is to plant their host trees. They require Silver Maples (Acer saccharinum) for their spring generation and Alders (Alnus spp.) for their summer and fall colonies. Maintaining a moist, riparian-like environment with these specific trees is key to bringing them to your yard.

Woolly Alder Aphid feed exclusively on plant sap. They use their needle-like mouthparts to pierce the tissue of maple leaves or alder twigs to reach the sugar-rich phloem. They do not eat the leaves themselves, but rather 'sip' the liquid energy from the tree.

Yes, they are quite common in suburban areas, especially in neighborhoods with older Silver Maple trees or near drainage ditches and ponds where Alders grow naturally. Because they look like white mold or fluff, many homeowners overlook them or mistake them for a plant disease.

While both produce white wax and 'dance,' the easiest way to tell them apart is the host tree. Woolly Alder Aphids are found on maples and alders, while Beech Blight Aphids are found exclusively on American Beech trees. Additionally, Woolly Alder Aphids tend to have longer, more trailing 'wool' than their beech-dwelling cousins.

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