Agromyzidae

 The Agromyzidae (Diptera) is an acalypterate family of small
flies found around the world. Currently, there are approximately 2750
described species, with many species awaiting formal description. The
Agromyzidae contains two subfamilies, the Agromyzinae and the
Phytomyzinae, and 29 (or so) genera, several of which are quite large
(>300 species). The external morphology of agromyzids is fairly
homogeneous and definitive species identification usually requires
dissection of the male genitalia or molecular diagnostics, such as DNA
barcoding.

All agromyzid larvae are "plant parasites" or phytophagous, feeding within living plant tissue. Although commonly known as "the leafmining flies," not all agromyzids
form leafmines -- species are also known which feed in plant stems,
flowerheads, fruits, petioles, roots, or cambium -- although leafminers
are most commonly collected because they are most conspicuous to casual inspection of their host plants. It
should be noted that agromyzids are not the only insects to form
leafmines; these are also produced by some species of sawflies, moths,
beetles, as well as some other flies.

Agromyzids are exceptionally interesting because of their host plant associations. Although agromyzids are recorded as feeding on plants in more than 140 plant families, most agromyzid species are highly specialized, often feeding on a single host plant species. This seemingly paradoxical pattern of broad polyphagy of agromyzids as a group contrasted with high degrees of specialization of individual species offers evolutionary biologists an exciting opportunity to study the patterns and processes associated with host shifts, speciation, and the evolution of dietary/ecological specialization.

Because agromyzids feed on so many different plant species, it is inevitable that some are agricultural pests. Some highly specialized agromyzid species achieve pest status simply because their host plant species happens to be grown as a crop or ornamental. A few agromyzid species, however, are broadly polyphagous and feed on several hundred plants species and/or crop varieties. These species can cause tremendous economic damage when populations grow to large numbers, and some species are known to rapidly evolve insecticide resistance, greatly impeeding management efforts. On the plus side, a few agromyzids have been used in programs for biologicol control of invasive weeds.