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

 

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 fly miner, the agromyzid Phytomyza ilicis, is recorded on Ilex, although a second species P. jucunda is recorded from mainland Europe on Ilex aquifolium and crenata (Bladmineerders van Europa).

Papp, L. & Černý, M. (2019). Agromyzidae (Diptera) of Hungary. Volume 4. Phytomyzinae III. 708 pp. Pars Ltd, Nagykovácsi, Hungar., regarding Hungarian reared specimens of P. ilicis, state; “Much to our surprise, after genitalia preparation we found that Kertész’s males, represent two species (from the same collection). We are afraid that all former records of P. ilicis from Europe will need to be either confirmed or revised.”

There are eleven other species known to utilise Holly in the Nearctic region (Lonsdale & Scheffer, 2011), whilst in Europe, P. jucunda also mines Holly. At present, it is not known if the second species mentioned by Papp & Černý relates to one of the other known Holly miners or is an undescribed species. Therefore when submitting records to the National Agromyzidae Recording Scheme, the anterior spiracles of the puparium must be examined and photographed. This will allow separation from some, not all, of the other possible species and rearing adult material will be necessary in some instances.

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


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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.

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

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.

Papp, L. & Černý, M. (2019). Agromyzidae (Diptera) of Hungary. Volume 4. Phytomyzinae III. 708 pp. Pars Ltd, Nagykovácsi, Hungar., regarding Hungarian reared specimens of P. ilicis, state; “Much to our surprise, after genitalia preparation we found that Kertész’s males, represent two species (from the same collection). We are afraid that all former records of P. ilicis from Europe will need to be either confirmed or revised.”

There are eleven other species known to utilise Holly in the Nearctic region (Lonsdale & Scheffer, 2011), whilst in Europe, P. jucunda also mines Holly. At present, it is not known if the second species mentioned by Papp & Černý relates to one of the other known Holly miners or is an undescribed species. Therefore when submitting records to the National Agromyzidae Recording Scheme, the anterior spiracles of the puparium must be examined and photographed. This will allow separation from some, not all, of the other possible species and rearing adult material will be necessary in some instances.

Phytomyza ilicis Curtis, 1846 [Diptera: Agromyzidae].
-> Leaf miner: Upper surface gallery, initially narrow and often for some length following the leaf margin, gradally strongly widening and then, specially in small leaves, forming a secondary blotch. Frass in small grains, forming an almost continuous black line in in the centre of the gallery (very unusual in Agromyzidae). Pupation in the mine; at the underside of the leaf a circular exit opening is prepared, closed by the epidermis. The, strikingly bifid anterior horns of the puparium protrude through the epidermis.

On Ilex aquifolium and Ilex crenata, but not yet in Britain.

Phytomyza jucunda Frost & Sasakawa, 1954 [Diptera: Agromyzidae]


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