Leafminers leave a trail between the upper and lower surfaces of leaves. They can be a pest on chrysanthemums, perennials and in landscapes. Leafminers may be the larvae of flies, caterpillars of moths or grubs of beetles. Leafminers are sometimes classified by the pattern of the mine which they create. Serpentine leaf mines leave winding trails in the leaves that widen as the insect grows. Various blotch leaf mines are irregularly rounded.
This photo is damage on aquilegia caused by a Columbine leafminer. Adults are tiny dark flies and females make leaf punctures (in photo) with their ovipositor so that they can feed on plant fluids. The presence of small puncture marks is a indication of activity of these insects and can be useful for timing insecticides applied for management.
In landscapes, columbine leafminers are more of an aesthetic problem and will not kill plants.