Garden Wildlife
             Garden Wildlife
Leaf-mining flies
 
Flies in several Diptera families have at least some species with larvae that feed inside the foliage.  These families include the Drosophilidae (fruit or vinegar flies), Scathophagidae (dung flies), Anthomyiidae, Tephritidae (fruit flies), Syrphidae (hoverflies) and Agromyzidae (leaf-mining flies).  Other insect orders with some leaf-mining species are the Lepidoptera (Butterflies and moths), Coleoptera (Beetles) and some sawflies in the Hymenoptera Bees ants and
wasps.
 
Species in Britain and Ireland.
 
The Agromyzidae has the greatest number of leaf-mining species likely to be seen in gardens.  Common species are the chrysanthemum leaf miner, Chromatomyia syngenesiae; holly leaf miner, Phytomyza ilicis; primrose leaf miner, Chromatomyia primulae; aquilegia leaf miners, Phytomyza aquilegiae and Phytomyza minuscula; delphinium leaf miner, Phytomyza aconiti; Astrantia leaf miner, Phytomyza astrantiae; laburnum leaf miner, Agromyza demeijerei; allium leaf miner, Phytomyza gymnostoma.  The last mentioned is a pest of onion, shallots, chives and leeks that became established in Britain in 2002.  Many wild flowers are also mined by agromyzid fly larvae.
 
 
A drosophilid (fruit or vinegar fly) leaf miner likely to be seen in gardens is Scaptomyza flava, which makes mines in the foliage of nasturtiums. It has the "hunched" appearance of other drosophilids.  Celery leaf miner, Euleia heraclei, is a tephritid fly that mines the foliage of celery, celeriac, lovage and other related plants.  The Syrphidae or hoverfly family, has some species with leaf-mining or stem-boring larvae.  Cheilosia caerulescens is a recently arrived syrphid fly with larvae that mine the fleshy leaves of house leek, Sempervivum species. The leaf-mining members of the Scathophagidae and Anthomyiidae are mainly associated with wild flowers, rather than garden plants. However, an anthomyid fly known as the beet leaf miner, Pegomya hyoscyami, mines the foliage of spinach beet, Swiss chard and beetroot.
 
 
Beet leaf miner Pegomya hyoscyami Left: typical damage on a leaf of chard, Right, larva inside peeled-back blister
 
Biology
 
The larvae of leaf-mining flies feed within leaves between the upper and lower epidermis.  In doing so, the larvae create mines that show up as white or brownish discoloured lines or blotches.  The pattern of the mine is fairly constant for a particular species of leaf miner.  In some species it is a linear tunnel that often twists and turns as the larva moves within the leaf. Other species create irregular blotch mines or a combination of linear and blotch mines.  In most species, each larva creates its own mine but the delphinium leaf miner Phytomyza aconiti, beet leaf miner and celery leaf miner have larvae that feed communally, creating large blotch mines. 
 
Life cycle 
 
Leaf-mining flies lay their eggs on or in the foliage of suitable host plants. After hatching, the larvae tunnel through the internal leaf tissues.  When they have completed their feeding, the larvae of some species pupate within the foliage but in others the larvae exit the mines and pupate in the soil.  Some species have several generations a year.  Most species overwinter as pupae. 
 
Role of leaf-mining flies in gardens
 
Some leaf-mining flies that develop on garden plants cause sufficient damage to their host plants for them to be regarded as pests.  In most cases, however, the damage is more of a cosmetic nature and is unlikely to affect the plant’s growth. 
 
Other sources of information
 
Website
Web site of British leaf-miners 
Website for Leaf and stem mines of British flies and other insects
RHS information on astrantia leaf miner fly
RHS information on chrysanthemum leaf miner fly
RHS information on beet leaf miner fly
RHS information on celery leaf mining fly
RHS information on holly leaf miner fly
RHS information on allium leaf miner fly
RHS information on sempervivum miner fly
RHS information on hellebore leaf miner fly
RHS information on echinops leaf miner fly
 
Books
Spencer, K. A. (1972) Handbooks for the Identification of British Insects Vol 10 part 5g. Diptera - Agromyzidae – out of print but available here.
 
 
Page text drafted by Andrew Halstead, reviewed by Andrew Salisbury, compiled by Steve Head
 
 
   Adult Leaf miner fly Napomyza bellidis                      Larva of holly leaf miner Phytomyza ilicis 
Examples of fly leaf miner damage. Top left: Primula leaf miner Chromatomyia primulae Top right: holly leaf miner Phytomyza ilicis  
 
Below left: Aquilegia linear leaf miner  Phytomyza minuscula Below right: Aquilegia blotch leaf miner Phytomyza aquilegiae 
 
Leaf mining flies. Left: nasturtium miner Scaptomyza flava (museum specimen)  Centre: Celery leaf miner, Euleia heraclei Right: Sempervivum miner fly Cheilosia caerulescens 
Leaf-mining flies
 
Flies in several Diptera families have at least some species with larvae that feed inside the foliage.  These families include the Drosophilidae (fruit or vinegar flies), Scathophagidae (dung flies), Anthomyiidae, Tephritidae (fruit flies), Syrphidae (hoverflies) and Agromyzidae (leaf-mining flies).  Other insect orders with some leaf-mining species are the Lepidoptera (Butterflies and moths), Coleoptera (Beetles) and some sawflies in the Hymenoptera Bees ants and
wasps.
 
Species in Britain and Ireland.
 
The Agromyzidae has the greatest number of leaf-mining species likely to be seen in gardens.  Common species are the chrysanthemum leaf miner, Chromatomyia syngenesiae; holly leaf miner, Phytomyza ilicis; primrose leaf miner, Chromatomyia primulae; aquilegia leaf miners, Phytomyza aquilegiae and Phytomyza minuscula; delphinium leaf miner, Phytomyza aconiti; Astrantia leaf miner, Phytomyza astrantiae; laburnum leaf miner, Agromyza demeijerei; allium leaf miner, Phytomyza gymnostoma.  The last mentioned is a pest of onion, shallots, chives and leeks that became established in Britain in 2002.  Many wild flowers are also mined by agromyzid fly larvae.
 
 
Examples of fly leaf miner damage. Top left: Primula leaf miner Chromatomyia primulae Top right: holly leaf miner Phytomyza ilicis  
 
Below left: Aquilegia linear leaf miner  Phytomyza minuscula Below right: Aquilegia blotch leaf miner Phytomyza aquilegiae 
 
Larva of holly leaf miner Phytomyza ilicis    Adult Leaf miner fly Napomyza bellidis      
A drosophilid (fruit or vinegar fly) leaf miner likely to be seen in gardens is Scaptomyza flava, which makes mines in the foliage of nasturtiums. It has the "hunched" appearance of other drosophilids.  Celery leaf miner, Euleia heraclei, is a tephritid fly that mines the foliage of celery, celeriac, lovage and other related plants. 
 
The Syrphidae or hoverfly family, has some species with leaf-mining or stem-boring larvae.  Cheilosia caerulescens is a recently arrived syrphid fly with larvae that mine the fleshy leaves of house leek, Sempervivum species. The leaf-mining members of the Scathophagidae and Anthomyiidae are mainly associated with wild flowers, rather than garden plants. However, an anthomyid fly known as the beet leaf miner, Pegomya hyoscyami, mines the foliage of spinach beet, Swiss chard and beetroot.
 
 
Leaf mining flies. Top Left: nasturtium miner Scaptomyza flava (museum specimen)  Top right: Celery leaf miner, Euleia heraclei 
 
Left: Sempervivum miner fly Cheilosia caerulescens 
Beet leaf miner Pegomya hyoscyami Left: typical damage on a leaf of chard, Right, larva inside peeled-back blister
 
Biology
 
The larvae of leaf-mining flies feed within leaves between the upper and lower epidermis.  In doing so, the larvae create mines that show up as white or brownish discoloured lines or blotches.  The pattern of the mine is fairly constant for a particular species of leaf miner.  In some species it is a linear tunnel that often twists and turns as the larva moves within the leaf. Other species create irregular blotch mines or a combination of linear and blotch mines.  In most species, each larva creates its own mine but the delphinium leaf miner Phytomyza aconiti, beet leaf miner and celery leaf miner have larvae that feed communally, creating large blotch mines. 
 
Life cycle 
 
Leaf-mining flies lay their eggs on or in the foliage of suitable host plants. After hatching, the larvae tunnel through the internal leaf tissues.  When they have completed their feeding, the larvae of some species pupate within the foliage but in others the larvae exit the mines and pupate in the soil.  Some species have several generations a year.  Most species overwinter as pupae. 
 
Role of leaf-mining flies in gardens
 
Some leaf-mining flies that develop on garden plants cause sufficient damage to their host plants for them to be regarded as pests.  In most cases, however, the damage is more of a cosmetic nature and is unlikely to affect the plant’s growth. 
 
Other sources of information
 
Website
Web site of British leaf-miners 
Website for Leaf and stem mines of British flies and other insects
RHS information on astrantia leaf miner fly
RHS information on chrysanthemum leaf miner fly
RHS information on beet leaf miner fly
RHS information on celery leaf mining fly
RHS information on holly leaf miner fly
RHS information on allium leaf miner fly
RHS information on sempervivum miner fly
RHS information on hellebore leaf miner fly
RHS information on echinops leaf miner fly
 
Books
Spencer, K. A. (1972) Handbooks for the Identification of British Insects Vol 10 part 5g. Diptera - Agromyzidae – out of print but available here.
 
 
Page text drafted by Andrew Halstead, reviewed by Andrew Salisbury, compiled by Steve Head