Why does your Rhododendron polycladum have tiny black flies? Diagnose the cause and fix it with our step-by-step guide.
The tiny black flies are likely fungus gnat adults, whose larvae thrive in the moist organic matter of Rhododendron potting soil. The larvae feed on decaying roots and fine root hairs, which can weaken the plant's ability to absorb water.
Rhododendrons require consistent moisture but are highly susceptible to root suffocation. Excessively wet soil creates the perfect breeding ground for fungus gnat larvae and can lead to Phytophthora root rot.
A thick layer of decomposing bark or compost around the base of the Rhododendron provides both food and habitat for small flies. As organic matter breaks down, it attracts moisture-loving insects.
Your plant might also be experiencing one of these issues:
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