D. emailed us to say that
I sprayed insecticide to prevent leaf miner damage on
the columbine but they're a mess of mines, anyway. What
Columbine leaf miner can be handled many ways:
ignoring it while it simply runs its
plucking leaves or
cutting the plant back.
Below, left: Columbine: It's SO PRETTY when it's blooming,
and free of insects. But it's a bit tatty after bloom, insects or
no (going, going... at center and right). So Option 4 actually becomes an
Option 1: Ignore it
Columbine leaf miner (one of a couple of insects like a fruit
fly; Phytomyza aquilegivora makes serpentine mines and
P. aquilegiana makes blotches) is not a threat to a
columbine's existence. It's just ugly, a leaf-spoiling nuisance.
However, if you are determined to reduce the damage:
your timing and insecticide may work
This insect species' larvae come out of the leaf as they
complete their mining phase, attach themselves to the plant and
pupate in about 2 weeks -- faster if it's warmer, more slowly if
it's very cool. Adults emerge as tiny flies that lay eggs on the
leaves. There may be two or more rounds of this in spring, until
eventually one generation of larvae drops into the soil and remains
there until the next spring, to emerge and lay eggs about the time
the flower stalks begin to lift above the columbine's foliage.
When each new generation of miners comes out of its eggs the
insects quickly chew into a leaf. There the plant itself protects
them from contact insecticides. Spray a bit early or late and you
miss the first flight of adults and/or the briefly exposed young,
and have to make a second pass. Insecticides that are absorbed into
the leaf to kill what eats them, can't stop all the damage. So this
insect is tough to control that way.
3: Get picky
- pluck off every bad leaf as you see it.
Picking off leaves as you see miner damage occur can keep the
insect's population down. However, when there is this much mining
damage, the insect's already had a good year!
4: Deny the pest its meal
Right now (late spring) when most if not all columbine miners
are inside columbine leaves, you can simply cut down your plants,
then burn or hot compost or steam the clippings inside a plastic
The plant will be fine. Sure, you lose a bit of flower but
that's not a big loss as the plant's past its peak bloom. What
blooms are left, you can cut for a vase.
Have no fear for the columbine if you cut it to the ground. It
will be fine. Below: That thick nub of a root, which can be
much larger on a plant older than this yearling, contains a lot of
starch and thus a lot of comeback.
Right: See it already producing new basal
Its new growth might grow unspoiled by miners, and certainly
look neater than the foliage of a stem that's bloomed out or
ripening seed. It may even produce a few more blooms.
about columbine problems from Connecticut's Ag Experimental