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A Bug is a Bug
by John Harmon
July 20, 2003

Last week I talked about leaf miners and some of the damage they have been doing around town. A fellow down in Atlin who read my column pointed out that I had identified the wrong bug. I said, "it's a tiny bug called a leaf miner. Scientifically it's known as Argyresthia thuiella. This pest is a tiny caterpillar (Lepidoptera) that primarily feeds on the leaves of deciduous trees".

The gentleman is correct. That particular bug Argyresthia thuiella attacks only coniferous trees and shrubs or plants with needles and not leaves, my mistake. I tend to try and stay away from Latin names in the first place. No sense in using a "dead" language unless you are an entomologist. I'm not and neither are most folks that garden so I try and give out some general information folks can use rather than specific information on a single bug. I try and stay away from Latin whenever I can.

The gentleman pointed out that the bug that attacks aspen is "probably Phyllocnistis populiella" and he is probably correct. Leaf miners are a huge group and would warrant an entire textbook to give them justice. I try to avoid textbooks too. He also pointed out that bugs names should be in Italics although I don't think the bugs or my editor are aware of that.

Phyllocnistis populiella is a member of this family of primarily leaf miners that pupate outside the mine so the part of last week's column about over wintering bugs in the leaves would also be incorrect for some bugs. Three of the more common genera are Lyonetia, Bucculatrix and Phyllocnistis. Bucculatrix pomifoliella makes a serpentine mine on apple leaves. Phyllocnistis populiella makes a serpentine mine on trembling aspen. Lyonetia alniella makes a blotch mine on alder. Other species of Lyonetia occur on Ceanothus and Vitis.

Regardless of which particular bug is attacking, most folks are only interested in what they can do about them. With the leaf miner the answer to that question is not much. As I pointed out there are a few insecticide sprays that can penetrate the leaf and kill them but not many. Picking the leaves is still a good way to get rid of some of them at least. Another method of control I didn't mention last week is to put out yellow sticky traps in the early spring to catch the adult moths before they can get started. So the options are to kill them early in the spring or catch them inside the leaf to destroy them.

The point is that no matter what its name, Latin or otherwise, a bug is a bug and leaf miners of one kind or another seem to be on a tear this year. The only good news is that Aspen and Poplar are extremely hard to kill off and these bugs probably won't be able to do it. The only plants you have to worry about are trees or shrubs that are borderline hardy in the north to begin with. When you are pushing the hardiness boundaries anyway a small thing like leaf miners (regardless of which specific leaf miners) can be the factor that determines success.

It's nice to know that folks in Atlin are reading my column and I'll try to be more careful in the future to correctly identify bugs just in case an entomologist happens across my column. However most of the time I find it difficult to correctly identify bugs especially when scraping them off my heel.



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