*3.1. Cydalima Perspectalis*

In total, in 2018–2020, thanks to gardeners and plant breeders, users of the website "The Allotment and the Garden Our Passion" were collecting information from 166 places (towns) in Poland in the form of 674 documented reports on the presence of *C. perspectalis* in all voivodeships (Figures 4–6 and Tables S1 and S2).



**Figure 4.** (**a**) The hypsometric and administrative map of Poland (source: https://pl.wikipedia.org/ wiki/) (accessed on 17 November 2021); (**b**) main road routes in Poland (source: https://www.google. pl/maps/---modified) (accessed on 17 November 2021); (**c**) administrative division of Poland into 16 voivodeships. (names of voivodships—see Table 1; 1–16: numbers assigned to individual voivodships).

**Figure 5.** The number of places (towns) where *Cydalima perspectalis* was recorded in individual voivodships in 2018–2020. Axis X: 1–16—numbers assigned to individual voivodships; see Table 1.

**Figure 6.** The number of confirmed records of *Cydalima perspectalis* occurrence in individual voivodeships in 2018–2020. Axis X: 1–16—numbers assigned to individual voivodships; see Table 1.

Three years of social monitoring of *C. perspectalis* in Poland allow us to conclude that there was an increase in the population size in all voivodeships each year, both in moth-controlled cities (new locations) and in the reported records. In the last 2020 year of research, we revealed the presence of box tree moths in Warmian-Masurian, Kuyavian-Pomeranian, and Podlaskie voivodeships (No.: 3, 6, and 8). The most significant increase in the number of new locations and reported records in 2020 compared to the previous year was found for voivodeships: Greater Poland, Masovia, Silesian, and Subcarpathian (No.: 5, 7, 14, and 16) (Figures 5 and 6).

In 2018, based on confirmed data from the gardening website, *C. perspectalis* was reported from 57 places. They were located within ten voivodeships (out of 16): Greater Poland, Masovian, Lower Silesian, Łód´z, Holy Cross, Lublin, Opole, Silesian, Lesser Poland, and Subcarpatian (No.: 5, 7, 9, 10, 11, 12, 13, 14, 15, and 16). Most information about damaged box trees came from the Silesian and Subcarpathian voivodeships (No.: 14 and 16) (Figure 7). The box tree moth spread in Poland in 2012–2017 from West to East (along with the arch of the Sudetes and the Outer Western Carpathians)—green arrows. It is the main road axis of southern Poland (A4 motorway) from West to East. However, the large number of discovered sites of *C. perspectalis* in 2016–2017 in the Subcarpathian Region (green oval) may be the result of an invasion of the boxwood moth from South Slovakia where its presence was recorded the first time in Zvolen, Košice, and Presov in 2013 [20,37].

**Figure 7.** The range of *Cydalima perspectalis* occurrence in Poland in 2018 and its possible routes of spread. Each grey point indicates the presence of a pest found in social monitoring in 2018; the green arrow marks the route for insects to spread until 2017 [25,26]; red lines and numbers indicate the main directions of the species expansion to the north in 2018; 1–16: numbers assigned to individual voivodships; see Table 1; n–r: extreme, key locations for the expansion of *C. perspectalis* in Poland, recorded in 2018—see the text below.

The northernmost points of the *C. perspectalis* range recorded in 2018 correspond to the main national and international south-north communication routes. These routes indicate their essential role in the spread of this species to the north of Poland. The most important of them are: the S5 clearway Wrocław-Pozna ´n (Leszno: n); S11-Opole-Pozna ´n (Kalisz: o); motorways: latitudinally running A4 from Opole via Katowice to Kraków along with the A1 motorway running north from Katowice to Łód´z (p) and further to Warsaw (q) and with the S7 clearway from Kraków to Warsaw (q); S19 from Rzeszów to Lublin with a branch to Zamo´s´c (r) (Figure 7).

In 2019, the presence of *C. perspectalis* was found in 77 localities located in 13 voivodeships. These were the same voivodeships as in the previous years. Additionally, the pest appeared in the country's west and the north in the following voivodeships: West Pomeranian, Pomeranian, and Lubusz (No.: 1, 2, and 4). The pest's appearance in Szczecin and Gda ´nsk, on the coast of the Baltic Sea, was a big surprise. This year, the most information about the species' appearance came from the south of Poland in the following voivodeships: Silesian, Lesser Poland, and Subcarpathian (No.: 14, 15, and 16) (Figure 8). The confirmed presence of *C. perspectalis* in Polish port cities on the Baltic Sea (Szczecin and Gda ´nsk) may result both from the movement along communication routes along the Odra and Warta river valleys (Szczecin) and/or from sea transport from Western Europe (or even from Asia)—the presence of moths in Gda ´nsk and Szczecin.

**Figure 8.** *Cydalima perspectalis* occurrence range in Poland in 2019 and its other possible routes of spread. Each grey point indicates the presence of a pest found in the course of social monitoring in 2019; red lines and numbers indicate the main directions of the species expansion to the north in 2019; 1–16: numbers assigned to individual voivodships; see Table 1; n–r: extreme, key locations for the expansion of *C. perspectalis* in Poland, recorded in 2019—see the text below.

Once again, major communication routes reflect the further spread of *C. perspectalis* to the north. These include: S3 Wrocław/Legnica-Szczecin clearway (report from Gorzów Wielkopolski n); clearway S5 to Pozna ´n (o); latitudinally running A2 Pozna ´n-Warsaw motorway (report from Konin: p). On the other hand, road routes of local importance, such as Warsaw-Bydgoszcz or Lublin-Puławy allowed insects to reach Płock (q) and Puławy (r)—places only about 100 km away from Warsaw or Łód ´z or 50 km from Lublin (Figure 8).

In 2020, there was a further large-scale expansion of *C. perspectalis* in Poland. Information about the pest's outbreak came from as many as 148 localities located in all 16 voivodeships that are part of Poland's administrative division. The last three voivodeships are Warmian-Masurian, Kuyavian-Pomeranian, and Podlaskie (No.: 3, 6, and 8). In addition to Gda ´nsk and Szczecin, the pest was recorded in such towns in the north of the country as Elbl ˛ag, Olsztyn, Ełk, Suwałki, and Bielsk Podlaski. The year 2020, however, confirmed earlier observations that currently *C. perspectalis* is most abundant in southern Poland, where it is warmer than in the north and where the vegetation period is slightly more extended (Figure 9).

**Figure 9.** *Cydalima perspectalis* occurrence range in Poland in 2020, and its final possible routes of spread. Each grey point indicates the presence of a pest found in the course of social monitoring in 2020; red lines and numbers indicate the main directions of the species expansion to the north in 2020; 1–16: numbers assigned to individual voivodships; see Table 1; n–r: extreme, key locations for the expansion of *C. perspectalis* in Poland, recorded in 2020—see the text below.

Data from 2020 confirms the role of the main national and international communication routes. The presence of *C. perspectalis* in Szczecin (n) reflects the route of clearway S3 (from Gorzów Wielkopolski) and S11 (from Pozna ´n). The presence of insects in Gda ´nsk (o) indicates a significant role of the A1 motorway along the main south-north communication axis and the S7 clearway from Warsaw to Gda ´nsk via Olsztyn and Elbl ˛ag (p). The main communication axes from Poland to the northeast to the border with Lithuania (clearway S62) made it easier for insects to reach Suwałki and Ełk (q) and to the border with Belarus (S8) to Bielsk Podlaski (r) (Figure 9).

The number of *C. perspectalis* records reported in 2020 is extremely interesting if the number of inhabitants is considered. Comparing only two voivodeships: Silesian and Subcarpathian (No.: 14 and 16)), where the number of reported records is similar (Figure 7), after such recalculation, the number of records from Silesia is comparable to other voivodeships in southern and western Poland. Despite its small area, the Silesian voivodeship (after the Masovian voivodeship with the capital of Warsaw) has the second largest number of inhabitants. A large number of records from the Subcarpathian voivodeship (No.: 16), with a relatively small number of inhabitants, probably results from the fact that the authors of the monitoring and website come from Rzeszów, where its excellent promotion took place (Figure 10).

**Figure 10.** The number of confirmed records of *Cydalima perspectalis* occurrence in individual voivodeships in 2020 per 1 M inhabitants. Axis X: 1–16—numbers assigned to individual voivodships; see Table 1.
