Leaf miner insects on columbine cause cosmetic damage

Bob Dluzen
Special to The Detroit News

Aquilegia, also called columbine, is an attractive and easy plant to grow in the garden. Although there is a native species, the most common ones grown are the European types. They have been hybridized by plant growers and are available in a wide variety of colors and shapes.

Since aquilegia is a perennial, once it’s planted it will come up every year. As a bonus it also produces viable seeds and will reseed itself. It is not an aggressive competitor so it’s not likely to over run a garden.

Like most plants, they have their own special set of problems. The most common pest likely to attack them is the columbine leaf miner, the maggot stage of a small, gnat-sized fly.

Leaf miner maggots cause damage while feeding on plant tissue between the top and bottom surfaces of the leaves. Unsightly tunnels are formed as they move continuously while chewing.

Even though nearly every leaf can be infested, leaf miners cause no real damage to the plant.

Because the miners live inside the leaf, they are protected from most insecticides. Fortunately, even though the leaves can look quite bad, the leaf miner doesn't seriously hurt the plant.

There are several generations of leaf miners each season. Spraying insecticides doesn't solve the problem and can actually make matters worse by killing off the leaf miners' natural enemies.

The best way to minimize the damage is to reduce their population by picking off and destroying any damaged leaves as they appear through the growing season. Then, in the fall, remove all of the old leaves and tops and dispose of them either by burning or placing in the household trash.

Placing them in the compost is not a good idea. To overwinter, the leaf miners enter into their pupal stage and may survive the composting process.