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This research on the occurrence of insects mining leaves of the English oak Quercus robur was performed between 2011–2012 in Bydgoszcz and in nine neighbouring sites: seven in forest areas and two in an urbanized environment. The analysis of the gathered material revealed the occurrence of insects from three different orders, Coleoptera, Hymenoptera and Lepidoptera, and 10 families: Curculionidae, Tenthredinidae, Bucculatricidae, Coleophoridae, Eriocraniidae, Gracillariidae, Heliozelidae, Incurvariidae, Nepticulidae and Tischeriidae. In total, 21 insect species were collected from Q. robur; most of them at forest sites. A slightly lower number of species was recorded at Janowo, where oaks were growing on the edge of the forest in the vicinity of a transport route with heavy traffic. Even fewer taxa were observed in the vicinity of urbanised areas; in the city park on the Bydgoszcz Canal and in Fordon. The most abundant species on the English oak were Tischeria ekebladella (Bjerk.) and Phyllonorycter heegeriella (Zell.).

Data on the parasitoid eulophid complexes reared from 6 species of leaf mining moths damaging the oak in the Middle Volga Area are reported. The reared eulophids belong to three subfamilies: Eulophinae (8 species from 6 genera): Cirrospilus diallus Walker, C. viticola (Rondani), Euplectrus liparidis Ferriere, Hyssopus geniculatus (Hartig), Sympiesis gordius (Walker), Pnigalio rotundiventris (Erdos), P. soemius (Walker), Rhicnopelte crassicornis (Nees); Entedoninae (11 species from 4 genera): Chrysocharis laomedon (Walker), Ch. prodice (Walker), Ch. pubens Delucchi, Ch. submutica Graham, Closterocerus formosus Westwood, Neochrysocharis aratus (Walker), Pediobius cassidae Erdos, P. flaviscapus (Thomson), P. metallicus (Nees), P. pyrgo Walker; and Tetrastichinae (3 species from 3 genera): Aprostocetus sp., Minotetrastichus frontalis (Nees), and Sigmophora brevicornis (Panzer). The most abundant of the moth parasitoids are M. frontalis and Ch. laomedon, while Tischeria ekebladella has the greatest number of parasitoids. The ectoparasitoids/endoparasitoids ratio in the number of species is 2: 1, and in the number of individuals reared, 1.76: 1. Thus, the host density is regulated primarily by the ectoparasitoids.

From the perspective of a specialist herbivore, how homogenous are individual tree crowns as patches of habitat? We partitioned variation in physical and chemical host leaf traits and in the abundance and performance of a specialist oak leaf miner, Tischeria ekebladella, into variation at different hierarchical levels. For the phenolic contents of the leaves, we examined variation among oak stands, among trees within stands and among branches within trees. For leaf size and water content, we assessed variation among trees within a single stand, among shoots within trees, and among leaves within shoots. For moth abundance and performance, we examined variation across all levels: among oak stands, among trees within stands, among branches within trees, among shoots within branches and among leaves and insect individuals. For measures of phenolic contents, we found little variation among stands but substantial variation among individual trees. Yet, a tree particularly rich in a given compound was often comparatively poor in another. At a finer spatial scale, the phenolic composition of individual parts of a single tree was quite consistent, whereas leaf weight and water content varied widely within individual tree crowns. Moth abundances varied more among shoots within branches than at any other spatial level, whereas moth survival showed equal levels of variation within individual shoots as among separate oak stands. Likewise, for four other measures of larval performance (assessed at the level of trees and lower), we found more variation within than between trees. In conclusion, the large variation observed in the performance of a specialist moth and in the physical traits of the leaves among different parts of single tree crowns refutes the image of an oak tree as an ‘island’ of internally homogeneous quality. Hence, we may expect little evolutionary adaptation of T. ekebladella at the scale of individual trees. The moths may instead evolve to behaviourally select their resource at a very fine scale. Large variation within trees also calls for extensive replication within trees in ecological sampling designs and/or the sampling of maximally similar leaves.

New distribution data for Tischeria dodonaea Stt. – a species recently discovered in Lithuania – are provided, together with distribution maps for both currently known Lithuanian tischeriid species: Tischeria ekebladella (Bjerk.) and T. Dodonaea Stt. Genitalia drawings of T. Dodonaea and leafmine photos of T. Ekebladella (Bjerk.) and T. Dodonaea are also given.

A total of 78 insect species were recorded as damaging plant organs (galls, mines and eaten leaves) on nine Quercus species in south-western Slovakia during 1987–1992. The insects belong to five orders: 41 species of Hymenoptera, 16 species of Lepidoptera, 13 species of Diptera, two species of Coleoptera and five species of Homoptera. In addition, galls of Eriophyes cerreus (Eriophyidae, Acari) were found. The following species were abundant: Andricus kollari (Htg.), A. lignicola (Htg.), A. lucida (Htg.), Neuroterus quercusbaccarum (L.), Biorrhiza pallida (Oliv.) (Hym., Cynipidae) and Periclista lineolata (Klug) (Hym., Tenthredinidae); Tischeria ekebladella (Bjerk.) (Lep., Tischeriidae) and Phyllonorycter (Lithocolletis) roboris Zll. (Lepidoptera, Gracillariidae); Haltica quercetorum Foundr. (Col., Chrysomelidae). The number of insect species moderately oscillated and changed during 1987–1992. The lowest number (35 species) was found in 1991, the highest (48 species) in 1989. The highest number, 42 insect species, was associated with Quercus cerris, the lowest (25 species) with Q. pubescens. Insect species caused a total of 6356 galls, mines and other types of damage on nine Quercus species. Insect species were evaluated according to degree of harmfulness.

The native leafmining moth Tischeria ekebladella (Lepidoptera: Tischeriidae) feeds on oaks and recently has become a pest of silviculture and urban green areas in central Europe. The behavioral responses of male moths to hexane extracts of whole bodies of calling females or males were tested under laboratory conditions. Only extracts of females elicited responses from males. Analysis of extracts by coupled gas chromatography/electroantennographic detection revealed the presence of two electroantennogram-active peaks. Structure elucidation of these compounds, by gas-chromatography/mass spectrometry and independent synthesis revealed them to be (3Z,6Z,9Z)-tricosa-3,6,9-triene and (3Z,6Z,9Z,19Z)-tricosa-3,6,9,19-tetraene. While the triene was present in both sexes, the tetraene was female-specific. The latter is a new structure for a pheromone component of Lepidoptera and a novel natural product. Field trapping tests, carried out in a mixed oak forest near Budapest (Hungary), using synthetic compounds applied to rubber dispensers, showed that the tetraene per se elicited catches of males in large numbers. When the triene was added to the tetraene in a ratio of 1:1, there was no increase in trap catch; the triene alone did not elicit catches of males. For monitoring this insect, the tetraene, applied to rubber dispensers at a dose of 300 μg, is a potent sex attractant.