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.

The most important pests of acacia black locust (Robinia pseudoacacia L.) (Fabaceae) are: Appendiseta robiniae Gillette, Phyllonorycter robiniella Clemens, Parectopa robiniella Clemens, Nematus tibialis Newman and Obolodiplosis robiniae Haldemann, species from North America, where it also originates the acacia, which is the host plant. In Europe these species were introduced accidentally, being considered invasive species. In Europe, O. robiniae Haldemann was first reported in July 2003 in northeastern Italy, in Paese near Padua, from where it spread to almost the entire European continent, especially through trade in infested biological material from nurseries. The attack occurs in the species R. pseudoacacia L., R. viscosa L. and R. hispida L., mainly in urban areas, where it mainly affects their aesthetic value. The larvae develop characteristic leaf margin roll galls on the infested leaves. There are up to 6 galels on a leaflet, and on average there are up to 5-6 larvae. In Europe it develops two, three and, in optimal conditions, even four generations a year. Zoophagous entomofauna can cause population decline, especially parasitoid species. For Platygaster robiniae Buhl & Duso (Hymenoptera: Platygastridae) the percentage of parasites reported was up to 40%. A low percentage of parasitism can be produced by other species, such as: Aprostocetus sp., Chrysocharis sp. (Hymenoptera: Eulophidae), Eupelmus urozonus Dalman (Hymenoptera: Eupelmidae), Eurytoma verticillata F. (Hymenoptera: Eurytomidae), Mesopolobus mediterraneus Mayr. (Hymenoptera: Pteromalidae) and Torymus sp (Hymenoptera: Torymidae).