Lace bug on azalea and rhododendron

I don't grow azaleas or rhododendrons at home in Melville -- deer pressure and sandy loam don't do them any favors -- so the bulk of this guide is sourced from Clemson HGIC, NC State Extension, Penn State Extension, and UC.

I don't grow azaleas or rhododendrons at home in Melville — deer pressure and sandy loam don't do them any favors — so the bulk of this guide is sourced from Clemson HGIC, NC State Extension, Penn State Extension, and UC IPM.

That said, lace bugs are one of the most common complaints from Long Island gardeners who do grow them. The damage pattern is distinctive enough that once you've seen it, you recognize it immediately: pale, washed-out foliage on a plant that looked perfectly healthy two weeks ago.

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What lace bugs are

Azalea lace bugs (Stephanitis pyrioides) and rhododendron lace bugs (Stephanitis rhododendri) are distinct species, though their damage and management are nearly identical. Per Clemson HGIC, adults are roughly 3–4 mm long and named for the lacy, net-like pattern on their wings and thorax. Under a hand lens, that pattern is unmistakable.

Adults overwinter as eggs inserted into leaf tissue on the underside of foliage, often covered with a brown, sticky tar-like excrement. Per NC State Extension, eggs hatch in April to early May in most of the Southeast and mid-Atlantic, producing pale spiny nymphs that aggregate on the undersides of leaves.

Most populations in the eastern United States complete two to three generations per year, with peak nymph activity in late May and again in July. Per Penn State Extension, in cooler climates like Pennsylvania and New York, two full generations are typical, with a partial third possible in warm years.