Evaluation of insect invasion indoors using indoor and outdoor light traps

Abstract

In order to evaluate the magnitude of insect invasion indoors under various light conditions, we compared light trap catches; one was set up outdoors, and the other was set up indoors in such a way that it did not leak its light to the outside. The ratio of the number of insects invaded that indoors to those captured with the outdoor light trap was used to evaluate invasion level because a positive correlation was found between them, and the number of insects that invaded indoors increased with the increase in those captured with the outdoor light trap. With a 10 cm open slit in the window, the ratio when both the room lights and the indoor light trap were turned on (4.1%) did not significantly differ from the ratio when only the room lights were turned on (5.7%). The ratio when neither the room lights nor the indoor light trap were turned on (0.6%) did not significantly differ from the ratio when only the indoor light trap was turned on (0.5%). Furthermore, the ratios were significantly higher under the former two conditions (4.1 and 5.7%) than under the latter two conditions (0.6 and 0.5%). Thus, the invasion of insects indoors was determined to be dependent on room light, and the indoor light traps did not affect the invasion of insects from outdoors.