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

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ILEX. Holly. [Aquifoliaceae]


Only one native species of Ilex is recorded in Britain - Holly (I. aquifolium). Highclere Holly (I. x altaclerensis) and Horned Holly (I. cornuta) are introduced.

Only one British miner, the agromyzid Phytomyza ilicis, is recorded on Ilex.

Holly - Ilex aquifolium. Image: © Brian Pitkin
Holly
Ilex aquifolium



Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Ilex


1 > Leaf miner: Oviposition takes place at the base of the petiole in a young leaf. Larva initially feeds in mid-rib, later producing characteristic irregular upper surface linear-blotch. Pupation internal (Spencer, 1972b: 81; Spencer, 1976: 433-4).

Oviposition, in May-June, in the underside of the petiole or midrib of a young leaf, leaves a clear scar. In the course of the following months the larva tunnels in the midrib in the direction of the leaf tip. Only in December-January it enters the leaf blade, where the fist moult takes place. The larva then makes an interparenchymatous blotch in the blade, in the middle layer of the (three cell layers thick) palisade parenchyma. Most frass is deposited in the centre of the blotch; here the epidermis often turns wine red. Often tha larva, not long before pupation, descends into the upper layers of the sponge parenchyma, and makes a large blotch there. This second mine, despite its size, is quite inconspicuous because there is no discolouration whatever. Pupation is within the mine, upper-surface, but lower-surface when a second blotch has been made. The anterior spiracles penetrate the epidermis (Bladmineerders van Europa).

Initially in mid-rib then upper surface blotch. Only miner on Holly. Widespread throughout. The early mine is green (British leafminers).

Monophagous. On Ilex aquifolium in Britain and elsewhere. Widespread throughout Britain. Also recorded in the Republic of Ireland. Common and Widespread in continental Europe. Introduced into western Canada and the north-west U.S.A.

Phytomyza ilicis Curtis, 1846 [Diptera: Agromyzidae].



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