Why does your Hydrangea macrophylla Magical Allegretto have tiny black flies? Diagnose the cause and fix it with our step-by-step guide.
The presence of tiny black flies in hydrangeas is most often due to Fungus Gnats, whose larvae thrive in the moist, organic-rich topsoil that 'Magical Allegretto' requires. The adults emerge to mate, while the larvae feed on decaying organic matter and fine root hairs.
Hydrangeas have high transpiration rates but are prone to root suffocation if the medium remains saturated. Constant moisture creates the perfect breeding ground for soil-dwelling insects like fungus gnats.
If using a peat-heavy potting mix for this cultivar, decomposing organic material can attract various small flies. These flies lay eggs in the moist debris, leading to a cycle of infestation.
Your plant might also be experiencing one of these issues:
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