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Boxwood Leafminer – ID and treatment options

Leafminer is a flying insect that lays eggs inside the leaves of your boxwood and then hatch and grow into small wormlike larvae. While inside the leaf they eat and feed off the boxwood, leaving it weakened and stressed.  You might have noticed that the outer portion of your boxwoods are yellowed, puckered and otherwise unhealthy looking.  This is where the leafminers are living. In a short time the leaf miners will start chewing and producing a loud chattering noise and then emerge as a winged adult, breed, and deposit more eggs in your boxwood continuing the cycle until your boxwood is either dead or extremely diseased. There are several things you can do to due to fix this problem as it will only get worse if left untreated.  The best option is to use a systemic insecticide with imadicloprid which causes your plant to become toxic to insects and kills any eggs laid within the leaves to die.  You can also spray with a foliar spray that has some residual while they are flying around, although it is difficult to get the timing down especially if you are working.  Finally if you would like to go with a non chemical approach you can prune off the infected chattering leaves (this must be done before they hatch, like today) and destroy them (garbage bag) or bury them well.  Wilt stop (pine oil) or All Seasons Oil can also be tried for another chemical alternative.  Finally, when treating this it’s important to fertilize the boxwood because the plant is stressed and needs help.  Stop in and we can assist you if you have noticed this problem.  It is very common and can be treated.

Leaf miner larvae inside a boxwood leaf