Observations on the brood-care behavior in Theridion japonicum (Theridiidae) were carried out under a laboratory condition by using a video tape recorder.
When a mother spider discovered a prey, she captured and chewed up the prey. Spiderlings began to crowd around the prey and clustered to suck it up about 17 min. later. After about 105 min., they dispersed gradually.
The mother spider fed spiderlings in this way for about 3 weeks until the spiderlings began to take prey by themselves. When the spiderlings were about 7 weeks old, the mother died and her body was sucked out by the spiderlings. Then, spiderlings dispersed and started solitary life.
Thus, Theridion japonicum will be ranked as “periodic-social” according to KULLMANN'S classification.
Arachnological Society of Japan