Summary1. We show that the population ecology of the 9-to 10-year cyclic, broadleaf-defoliating winter moth (Operophtera brumata) and other early-season geometrids cannot be fully understood on a local scale unless population behaviour is known on a European scale. 2. Qualitative and quantitative data on O. brumata outbreaks were obtained from published sources and previously unpublished material provided by authors of this article. Data cover six decades from the 1950s to the first decade of twenty-first century and most European countries, giving new information fundamental for the understanding of the population ecology of O. brumata. 3. Analyses on epicentral, regional and continental scales show that in each decade, a wave of O. brumata outbreaks travelled across Europe. 4. On average, the waves moved unidirectionally ESE-WNW, that is, toward the Scandes and the Atlantic. When one wave reached the Atlantic coast after 9-10 years, the next one started in East Europe to travel the same c. 3000 km distance. 5. The average wave speed and wavelength was 330 km year À1 and 3135 km, respectively, the high speed being incongruous with sedentary geometrid populations. 6. A mapping of the wave of the 1990s revealed that this wave travelled in a straight E-W direction. It therefore passed the Scandes diagonally first in the north on its way westward. Within the frame of the Scandes, this caused the illusion that the wave moved N-S. In analogy, outbreaks described previously as moving S-N or occurring contemporaneously along the Scandes were probably the result of continental-scale waves meeting the Scandes obliquely from the south or in parallel. 7. In the steppe zone of eastern-most and south-east Europe, outbreaks of the winter moth did not participate in the waves. Here, broadleaved stands are small and widely separated. This makes the zone hostile to short-distance dispersal between O. brumata subpopulations and prevents synchronization within meta-populations. Journal of Animal Ecology 2013Ecology , 82, 84-95 doi: 10.1111Ecology /j.1365Ecology -2656Ecology .2012 8. We hypothesize that hostile boundary models, involving reciprocal host-herbivore-enemy reactions at the transition between the steppe and the broadleaved forest zones, offer the best explanation to the origin of outbreak waves. These results have theoretical and practical implications and indicate that multidisciplinary, continentally coordinated studies are essential for an understanding of the spatiotemporal behaviour of cyclic animal populations.

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The species composition and abundance of phoretic mites of the bark beetles Pityokteines curvidens, P. spinidens, and P. vorontzowi on Silver Wr (Abies alba) were investigated in 2003 at two locations (Trakoscan and Litoric) in Croatia. Stem sections and branches from A. alba trees infested by Pityokteines ssp. were collected and incubated in rearing cages. Bark beetles emerging from the stem sections and branches were examined for photetic mites. A total of ten mite species were documented for the Wrst time as associates of Pityokteines spp. on A. alba. These included Dendrolaelaps quadrisetus, Ereynetes scutulis, Histiostoma piceae, Paraleius leontonychus, Pleuronectocelaeno japonica, Proctolaelaps hystricoides, Schizostethus simulatrix, Tarsonemus minimax, Trichouropoda lamellose, and Uroobovella ipidis. T. minimax was the most frequent phoretic mite of all the three scolytines and U. ipidis was also common, whereas, the other mite species occurred less frequently. The species spectrum and relative abundance of mite associates were similar for all three Pityokteines species. Another species, Pleuronectocelaeno barbara was commonly found phoretic on P. curvidens, captured in pheromone traps in 2005 at the location Litoric. Furthermore, two previously collected mite specimens from Switzerland, phoretic on P. curvidens, were identiWed as Nanacarus sp. and Bonomia sp. The records from Croatia and Switzerland in the present study increase the number of known mite associates of Pityokteines spp. from one previously documented species to 14 species. None of the phoretic mites found in the survey in Croatia appear to have the potential to be used for biological control of Pityokteines spp., although the feeding habits are unknown for many species recorded.

A description of the hitherto unknown larvae of Drusus radovanovici septentrionis Marinković-Gospodnetić, 1976 and Drusus croaticus Marinković-Gospodnetić, 1971 is given. The most important diagnostic features enabling separation from larvae of the other Drusinae are listed and illustrated. Larvae of D. croaticus are distinguished by the combination of specific morphological features (e.g. shape of head and pronotum, the absence of mandible teeth, the absence of prominent, black median setae on frontal margin of pronotum etc.). Besides the above mentioned, larvae of D. radovanovici septentrionis are primarily distinguished by distinct spinules on the head capsule. Some ecological notes are given and the life cycle of both species is discussed. Regarding the feeding behaviour, both analyzed species seem to be predominantly grazers. Both species were recorded in different spring types in the Dinarides. D. radovanovici septentrionis is known only from three springs in Bosnia and Herzegovina (springs of the Rivers Pliva, Bistrica and Sturba), while D. croaticus was recorded in 19 different springs in Croatia. Additionally, all Trichopteran species recorded from the sampled springs are listed.

1 The horse-chestnut leafminer, Cameraria ohridella Deschka & Dimic, was discovered during a mass outbreak on planted horse-chestnut trees, Aesculus hippocastanum, near Lake Ohrid in Macedonia. However, several peculiarities in the leafminer's biology and ecology, such as its inefficient control through natural enemies, indicate that it may be of exotic origin. 2 In this study, the parasitism of C. ohridella was examined in natural and artificial horse-chestnut stands in South-eastern Europe. The size and composition of the parasitoid complex of natural stands was comparable with that known from artificial stands. No specialist parasitoid species were detected in any of the samples. The only parasitoid species found exclusively in natural stands during this investigation were the braconid Colastes braconius and the eulophid Chrysocharis phryne. Both are known to be polyphagous on many leafminers in Europe and C. braconius has been often recorded from C. ohridella in artificial stands in previous studies. Parasitism levels varied within the same range (3.6-21.0%) throughout the entire region, in both types of habitats. 3 These results suggest that the parasitoid complex of C. ohridella in natural and planted horse-chestnut stands in Europe is typically that of an exotic, recently introduced leafminer. Consequently, C. ohridella is probably not indigenous in the Balkans, but has been introduced to the area of its discovery from another continent.