Hello,
The azalea lace bug is a non-native insect that has been causing yellowing or bronzing to azaleas and rhodies since it arrived. 

Keeping your plant healthy through irrigation and proper fertilization can also help the plant stay healthy. If the shrub is smaller you can spray off the insects with water in spring after the nymphs appear on the undersides of the leaves. There are also approved insecticides in this publication below if this becomes necessary. Be sure to follow all pesticide label instructions.
https://hortsense.cahnrs.wsu.edu/fact-sheet/azalea-azalea-lace-bug/

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