DIPTERA > BRACHYCERA | Higher Diptera

MUSCOMORPHA > SCHIZOPHORA > Acalypratae > Opomyzoidea > Agromyzidae (425 species)

(subfamilies: Agromyzinae and Phytomyzinae)

Apart from gnats and midges, the agromyzid leaf-mining flies are the largest Diptera family group yet, despite the large number of species, taxanomically there are just two subfamilies and 18 genera.

The larvae are all phytophagous; feeders of plant tissue. Most species, as the common name of the family suggests, develop inside leaves using their tiny mandibles to slowly chomp through their chosen host plant leaving their telltale mine streak in their wake. The mine can be a relatively simple linear trail or something more intricate with swirls or patterns, and with some species the trails are densely packed and referred to as blotch mines. The interesting thing is, that although the individual mines can vary considerably, the general appearance essentially remains constant for each species and, consequently, in conjunction with knowing the identity of the host plant, it is usually possible to determine the species.

Finding and studying leaf mines is, in my opinion, a completely separate science. There's also the added problem that leaf mines are produced by many different species. In respect of Diptera alone, there are a number of other families, such as the Anthomyiidae and Tephritidae for example, which include some leaf-mining species. But there are also many other leaf-miners in other insect orders, notably Lepidoptera and Hymenoptera.

The Agromyzidae though, also includes species where the larvae feed on other parts of a plant; the stems, seeds, roots or, with trees, twigs or even on young trunks. A small number also form galls.

Adults occur in a wide range of habitats depending on the larval host plant, but they are generally very small, rather inconspicuous flies which, apart from a small number of species that can be swept from grassland or low vegetation, are seldom seen let alone photographed.  

For this reason, the members of this family are mainly represented by photos of the mines. I may try to find a few examples but, in the meantime, I wanted to make sure that the family was referenced within my Diptera collection.

The main resource is the excellent National Agromyzidae Recording Scheme website where every species is listed with details of the host plant(s), descriptions of both the mines and the adults, distribution data and status, and an associated image gallery. Admittedly I've only flicked through as there are so many species, but it quickly becomes apparent that very few species include photos of an adult fly.

Purely down to luck, I photographed the species featured below which I initially thought was a chloropid grass fly. However, once the photo was on the computer I realised it wasn't and was pleasantly surprised to discover that it was a leaf-miner, and a species that could be identified.   

Phytomyza ranunculi -  a member of the largest genus of 121 species. As their name suggests, the larvae feed on various plants in the Ranunculaceae (buttercup) family. They form a long linear mine with frass in closely spaced grains. The species is common and widespread. The adults are tiny with a wing span of around 3mm. There are two generations. The overwintering generation seen during the summer months are conspicuously darker, whereas the autumn generation, as the individual featured here, is primarially yellow. In the dark form, both the hind-margin of the eye and the mesonotum are black, the pleura mostly so, and the scutellum only narrowly yellow centrally. In the paler form, the hind-margin of the eye is always yellow, as are the pleura and scutellum. The mesonotum is usually pale grey, sometimes rusty-orange, and invariably divided into bands. In both cases the third antennal segment is black. Intermediate colour forms can also occur.  

New page added, Nov.24