The leaf and stem mines of British flies and other insects
 

(Coleoptera, Diptera, Hymenoptera and Lepidoptera)

by Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds

  

Dialectica imperialella (Zeller, 1847)
[Lepidoptera: Gracillariidae]

Fen Slender

Gracilaria imperialella Zeller, 1847
Dialectica imperialella (Zeller, 1847).

Leaf-miner: The initial gallery is soon absorbed into a blotch. The blotch is squarish as the larva eats through the leaf parenchyma to the upper epidermis. the blotch turns brown and care must be taken to distinguish these mines from diptera - which can form blackish blotches (British leafminers). The larva makes a small, lower-surface spiralling corridor that soon gives way to a blotch that overuns the previous work. Gradually the mine becomes deeper, and finally is locally full depth. Only then the mine is apparent from above as some disconnected brownish spots. On the underside the mine is larger, membranous. The frass initially is in strings, but later it becomes a network of thin threads. Pupation usually is outside the mine (Bladmineerders van Europa).

Larva: The larvae of moths have a head capsule and chewing mouthparts with opposable mandibles (see video of a gracillarid larva feeding), six thoracic legs and abdominal legs (see examples).The larva is illustrated in British leafminers and Bladmineerders van Europa.

Pupa: The pupae of moths have visible head appendages, wings and legs which lie in sheaths (see examples).

Adult: The adult is not illustrated in UKMoths (check for update). The adult is illustrated in the NHM Cockayne Collection. The species is included in mothdissection.co.uk.

Hosts in Great Britain and Ireland:

Boraginaceae        
Pulmonaria officinalis Lungwort British Wild Flowers by John Somerville et al. British leafminers
Pulmonaria officinalis Lungwort British Wild Flowers by John Somerville et al. Pitkin & Plant
Symphytum officinale Common Comfrey British Wild Flowers by John Somerville et al. British leafminers
Symphytum officinale Common Comfrey British Wild Flowers by John Somerville et al. Pitkin & Plant

Hosts elsewhere:

Boraginaceae        
Lithospermum officinale Common Gromwell British Wild Flowers by John Somerville et al. Belgian Lepidoptera
Lithospermum officinale Common Gromwell   Bladmineerders van Europa
Lithospermum purpurocaeruleum Purple Gromwell British Wild Flowers by John Somerville et al.

Bladmineerders van Europa, as Buglossoides purpurocaerulea
Pulmonaria officinalis Lungwort British Wild Flowers by John Somerville et al. Belgian Lepidoptera
Pulmonaria angustifolia     Bladmineerders van Europa
Symphytum officinale Common Comfrey British Wild Flowers by John Somerville et al. Belgian Lepidoptera
Symphytum officinale Common Comfrey British Wild Flowers by John Somerville et al. Bladmineerders van Europa

Time of year - larvae: August-September (British leafminers).

Time of year - adults: Currently unknown.

Distribution in Great Britain and Ireland: Britain including Cambridgeshire, Dorset, Huntingdonshire and Isle of Wight (NBN Atlas).

See also British leafminers distribution map.

Distribution elsewhere: Widespread in continental Europe including Austria, Belgium, Czech Republic, Danish mainland, French mainland, Germany, Hungary, Italian mainland, Luxembourg, Poland, Romania, Russia - Central, Slovakia, The Netherlands and Ukraine. Also recorded in Near East and North Africa (Fauna Europaea).

NBN Atlas links to known host species:

Lithospermum officinale, Lithospermum purpurocaeruleum, Pulmonaria angustifolia, Pulmonaria officinalis, Symphytum officinale

British and Irish Parasitoids in Britain and elsewhere:

Ichneumonoidea - Links to species no longer available  
Diadegma lithocolletis Horstmann, 1969 Ichneumonidae: Campopleginae

External links: Search the internet:

Belgian Lepidoptera
Biodiversity Heritage Library
Bladmineerders van Europa
British leafminers
Encyclopedia of Life
Fauna Europaea
NBN Atlas
NHM UK Checklist
UKMoths

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 Last updated 11-Jul-2019  Brian Pitkin Top of page