Phototaxis Characteristics of Lymantria xylina (Lepidoptera: Erebidae)

<i>Lymantria xylina</i> Swinhoe (Lepidoptera: Erebidae) is considered a potentially internationally invasive forest pest with limited knowledge about its phototactic behavior. This study investigated the phototaxis of <i>L. xylina</i> males and females using various insecticidal lamps in the field. The results showed that all lamps attracted both males and females, but females were captured in a very low numbers, with a female-to-male ratio of 1:322. The insecticidal lamp with a peak wavelength of 363 nm was most effective for male trapping. Males exhibited a distinct light-trapping rhythm, peaking around midnight (23:00-0:00), with 29.5% capture, while females were most active at dusk (19:00-20:00), with 44.4% capture. Light-trapped females were smaller and lighter than indoor-emerged females and had lower egg-carrying capacity. Females, when laying eggs, did not exhibit phototactic behavior. Only 14.6% of non-ovipositing females showed phototactic behavior, and only 0.6% flew directly toward the lamp. These findings suggest that while non-ovipositing females can exhibit phototaxis, only a small proportion will, potentially reducing the risk of long-distance dispersal of <i>L. xylina</i> via ocean-going freighters. The results showed that the non-ovipositing females could fly under phototaxis, but their phototaxis was limited. This study provides a basis for the risk assessment of the long-distance dispersal of <i>L. xylina</i> via ocean-going freighters through female moth phototactic flight.