In landscaping, one of the frequently used plants is Buxus sempervirens L. The aesthetic value of these plants are often affected by the pests species that attack the leaves. The main species that attacks the Buxus spp. plants are: Monarthropalpus buxi Geoff., Psylla buxi L. and Cydalima perspectalis Walker. The attack of these species cause the drying of the plants.The Box Tree Moth, Cydalima perspectalis Walker., is a new species, on the European continent, being first recorded în 2006. In Romania, this species was reported in 2010, near Bucharest, from where it has been spread throughout the country. In Cluj has been reported in 2015. For establishing some control strategies, for this, it is necessary to know the bioecology of this species, depending on the specific environmental conditions of each area where the attack is present. In 2016 we have started the investigations to study the biological cycle, in Cluj area. The investigations were conducted in the laboratory and on the campus of UASVM Cluj-Napoca. In the investigated area, the species develops two full generations, and the third generation is partial. The adults of hibernating generation fly in the first decade of June until the first decade of July. Summer generation adults fly from the first decade of August, creating the second generation and the adults who establish the third generation (partial generation) fly in the second half of September. The incubation is between 5-6 days. Larval stage is between 29-38 days, pupal stage last from 10 to 14 days.

The species of pear sucker, also called pear psylla or pear psyllid, which are destructive insects belonging to the genus Cacopsylla (Hemiptera: Psyllidae) cause substantial damage to pear tree plantations. Two consecutive years of research were conducted on the population structure and biological cycle of psylla in a small, elderly, and unmaintained pear orchard in northern Romania. Of the two identified species (C. pyri L. and C. pyricola Forster), C. pyri dominated the psylla population with a percentage of 77.8-80.1%. Adults of both species emerge from hibernation in the first part of March and produce three generations per year. First-generation adults emerge in the first decade of June, the second generation in the last decade of July, and the third generation in the first decade of September as they enter the hibernation phase. Larvae of the first generation appear in the second half of April, the second generation at the end of June - the beginning of July, and the third generation in the second decade of August. There have been reports of up to 11 adults and 27 larvae per leaf, 9 larvae per petiole, and 14 larvae per fruit. The number of adults captured on yellow sticky traps exposed on the southern side of the tree crown was significantly higher compared to the northern side. Following the intense attack, the well-known cv. ‘Williams’ was heavily affected, pear trees were badly defoliated, blackened, and aged prematurely. The climatic conditions of the two years did not influence the phenology of the pests, but the importance of monitoring psyllids is widely argued, considering that it remains the key to integrated protection programs in pear orchards.

In Europe, the box tree moth, Cydalima perspectalis (Walker, 1859) was first reported in 2006, in southwestern Germany, then spread to almost all countries. Larvae of this species affect the aesthetic value of the box tree. In the last period, numerous studies were carried out regarding the identification of useful entomofauna that reduce the numerical density of the population of Cydalima perspectalis. In this study conducted in north-western Romania (Cluj County, in 2019), entomopathogens and useful entomofauna were monitored in four areas, represented by four cities. The entomopathogenic agents contaminated the larvae of the box tree moth in a proportion of 5.6% at Gherla, 6.8% at Dej, 8.7% at Cluj-Napoca and 15.3% at Ciucea. Most larvae have been infected with Bacillus. At Cluj-Napoca and Ciucea, the presence of the larval endoparasite Exorista larvarum L. (Diptera: Tachinidae) was reported. Parasitoid species determined a parasitization rate of 5.1% at Dej, 8.6% at Gherla and 13.4% at Cluj-Napoca. Predators affected pupae in a proportion of 3.8% at Gherla, 4.2% at Dej and 16% at Cluj-Napoca. Among the pupae predators, for the first-time common earwig was reported, Forficula auricularia L. Entomopathogenic agents affected 5.3% of the pupae collected from Cluj-Napoca, 7.7% in Gherla and 12.5% in Dej. During the monitoring period of the zoophagous entomofauna and the entomopathogenic microorganisms, affected the pupae in a percentage of 20.1% in Gherla, 21.8% in Dej, 34.7% in Cluj-Napoca, contributing to the diminution of the population of the harmful species.

Obolodiplosis robiniae Haldeman (Diptera: Cecidomyiidae) is a monophagous species, the host plants being species of the genus Robinia. The species is native to the U.S.A., and in Europe, it was first reported in Italy, in 2003, from where it spread to all European countries. In Romania, it was reported in 2007. The attack of this species is produced by the larval stage and manifests leaves. After hatching, the endophytic and gregarious larvae cause changes in the parenchyma structure that lead to the appearance of characteristic galls located at the edge of the leaflet and rolled towards its lower part. In 2021, we monitored the frequency of attacked acacia leaves, the number of galls reported on a leaflet and the number of larvae in a gala in two locations in Cluj-Napoca: on the acacias in the Central Park of the city and on the acacias in some street alignments. In the case of acacias in Central Park, the frequency of attacked fruits was 15%, and in the case of acacias in the alignment, 7%. On the 50 attacked leaves taken from Central Park, there were 932 leaflets, of which 40% are with galls, and the leaves on the alignment had 1010 leaflets, of which 19.2% are with galls. The number of galas/leaflets was between 1 and 5 galas in Central Park, and on alignments between 1 and 4 galas. In both locations, most of the leaflets were with a single gala. The maximum larvae/gala was five specimens in Central Park and three larvae on the leaflets on the alignment.

Species of ornamental trees and shrubs are frequently attacked by invasive species recently introduced in Romania. Of these, the species Metcalfa pruinosa Say. (Hemiptera: Flatidae), native to the United States, is widespread. It is a polyphagous species. The attack is manifested in the leaves causing damage to the aesthetic value of the attacked plants. During the 2020-2021, the species of trees and shrubs attacked by Metcalfa pruinosa Say were identified and the frequency and intensity of the attack was determined. The studies were carried out in the spaces see and on the street alignments in Cluj-Napoca. Observations were made on all plant species to determine the frequency of the attacked leaves. The species we reported on 47 species that systematically belong to 23 families. Metcalfa pruinosa Say. was reported on most plants, and the most attacked plants were: Ligustrum vulgare L., Fraxinus excelsior L., Robinia pseudoacacia L., Aesculus hippocastanum L., Acer platanoides L., Buxus sempervirens L., Thuja accidentalis L.