Question
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Followup To
Question -
Don't know if these attack forests, maybe only ornamental trees.
I have a young serviceberry.  Arborist tells me to expect leaf miners and to spray one time [w/ what he did not say] when larva are within leaves.
Online source says there is no spray, damage is cosmetic, and that I should collect the mature insects as they drop beneath the tree!
Help??

Answer -
The leaf miners are harder to kill since they are inside the leaf surface. An insecticide that will go into the leaf is called a systemic insecicide. I would recommend trying Dimethoate. Dimethoate is most effective if foliage is sprayed thoroughly when mines first appear in late April to early May. Check with your local garden type store fro Dimethoate or maybe another systemic insecticide for trees or plants.  As any leaves fall rake them and distroy the leaves--this will cut down the next generation of miners. In any case the miners will not kill your tree but makes it look ragged.
Other questions:  I'm in Iowa, no leaf miners yet.  Maybe there won't be any this year??  Also, I could expect to see them every year, or yearly until a certain age, or what?


Answer
Insect populations run in cycles--depending on the weather usually. Some years the population is high other years there seems to be no problem. I would watch the plants and at the first sign of miners then spray. No need to spray unless there is a problem. No unfortunately miners can attack at any age.