Table 1.

Temporal relationships between field survey and trajectory analysis of S. frugiperda found in Korea and Japan in 2019

Locations	Date of caterpillars found	Instar	Direct degree‐day estimation †	Temporal range for trajectory analysis ‡
Jeju Island	13 June	1–3	23–27 May	19–29 May §
Gochang, Jeonbuk	21 June	3–4	2–5 June	31 May–7 June
Minamikyushu, Kagoshima	27 June	5–6	6–11 June	27 May–13 June
Bungoohno, Ooita	12 July	5–6	20–25 June	7–27 June ¶
Asagiri, Kumamoto	11 July	5–6	17–23 June	7–25 June
Miyakonojo, Miyazaki	12 July	5–6	16–21 June	6–23 June
Nakatane, Kagoshima	3 July	5–6	14–19 June	4–21 June
Onna, Okinawa	11 July	5–6	27–30 June	17 June–1 July

^† The latest day of the direct degree‐day estimation was calculated by assuming the oldest larva just molted from its previous instar, and the earliest day by assuming the oldest larva would molt into the next instar soon.

^‡ The temporal range for trajectory analysis (i.e. probable arrival date) is the period of degree‐day estimation shifting 2 d earlier and 2 d later. In the Japanese cases, only old caterpillars were found in fields, but no young caterpillars. Therefore, it was suspected that some caterpillars already turned into the pupa stage and hid in the soil. As adults can survive at least approximately 10 d, the earliest degree‐day estimation was shifted by 10 d earlier as the first day for trajectory analysis.

^§ No trajectories were found from Guangdong, Guangxi, Hainan and Yunnan Provinces during 22–29 May for this site, and trajectories were calculated for the other three previous days 19–21 May.

^¶ No valid trajectories were found during 10–27 June for this site, and trajectories were calculated for during 7–9 June.