Elachista utonella is a moth

Moth

A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

 of the Elachistidae

Elachistidae

| image = Elachista rufocinerea 2.jpg| image_width = 240px| image_caption = Adult Elachista rufocinerea,demonstrating its tiny size versus an aphid and a spider mite | regnum = Animalia| phylum = Arthropoda| classis = Insecta...

 family. It is found from Fennoscandia

Fennoscandia

Fennoscandia and Fenno-Scandinavia are geographic and geological terms used to describe the Scandinavian Peninsula, the Kola Peninsula, Karelia and Finland...

 to the Pyrenees

Pyrenees

The Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...

 and Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 and from Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 to Romania

Romania

Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...

.
The wingspan

Wingspan

The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...

 is 8-9 mm. There is one generation per year in Great Britain, but there are possibly two generations in continental Europe.

The larvae feed on Carex acutiformis

Carex acutiformis

Carex acutiformis, the lesser pond sedge, is a species of sedge.-Description:It grows up to tall, with leaves up to long and wide.-Ecology:...

, Carex brizoides, Carex distans, Carex disticha

Carex disticha

Carex disticha is a species of sedge, whose common name is Two-ranked Sedge. It is native to parts of Northern and Western Europe, where it grows in moist spots in a number of habitat types, and it has been introduced to the Great Lakes region of southern Canada...

, Carex echinata

Carex echinata

Carex echinata is a species of sedge known by the common names star sedge and little prickly sedge.-Distribution:This plant is native to North and Central America and parts of Eurasia. Carex echinata is a plant of wet forests, marshes, and mountain meadows of moderate elevation...

, Carex elata, Carex flacca

Carex flacca

Carex flacca, with common names blue sedge, gray carex, glaucous sedge, or carnation-grass, , is a species of sedge native to parts of Europe and North Africa....

, Carex hirta

Carex hirta

Carex hirta, the hairy sedge, is a species of sedge found across Europe. It has characteristic hairy leaves and inflorescences, and is the type species of the genus Carex.-Description:...

, Carex muricata, Carex paniculata, Carex remota, Carex riparia

Carex riparia

Carex riparia, the greater pond sedge, is a species of sedge found across Europe and Asia. It grows in a variety of wet habitats, and can be a dominant species in some swamps. It is Britain's largest Carex, growing up to tall, with glaucous leaves up to long...

, Carex spicata

Carex spicata

Carex spicata is a species of sedge in the genus Carex.-Description:The culms of Carex spicata are long and approximately triangular in section. The leaves are long and wide, with a distinct keel. The ligule, at the base of the leaf, is long, with a large amount of loose white tissue. C...

, Carex vesicaria

Carex vesicaria

Carex vesicaria is an essentially Holarctic species of sedge known by the common name Blister Sedge. The dried fibers, sometimes used as thermal insulation in polar regions, are known as sennegrass, saennegrass or similar, from the plant's Bokmål name Sennegras.-Distribution:This sedge is native to...

, Festuca, Juncus gerardi and Scirus sylvaticus. They mine

Leaf miner

Leaf miner is a term used to describe the larvae of many different species of insect which live in and eat the leaf tissue of plants. The vast majority of leaf-mining insects are moths , sawflies and flies , though some beetles and wasps also exhibit this behavior.Like Woodboring beetles, leaf...

 the leaves of their host plant. The mine The mine starts halfway the blade as an upwards running corridor. Later, it reverses its course and becomes an elongate blotch occupying half the width of the leaf. The frass

Frass

Frass is the fine powdery material phytophagous insects pass as waste after digesting plant parts. It causes plants to excrete chitinase due to high chitin levels, it is a natural bloom stimulant, and has high nutrient levels. Frass is known to have abundant amoeba, beneficial bacteria, and fungi...

is light green at first but becomes grey later. It is deposited in the lowest part of the mine. Pupation takes place outside of the mine. They are yellowish green to greyish with a black head.