The spices I found in my yard is ダンゴムシ ,called pill bugs or wood louse in English.
I used to play with it when I was little because it was fun watching it roll up into a ball in my hand. When I was playing with my neighbor’s kids during Golden Week, I found pill bugs under a rock and I thought it would be interesting to do research about it.
Pill bugs are usually found in dark and moist places such as under rocks or logs. They can breed throughout the year. The female carries the eggs in a brood pouch on the underside of her body. Often, there are as many as 200 eggs per brood. The eggs hatch in 3 to 7 weeks, and the young remain in the pouch another 6 to 7 weeks. Once the young leave the pouch, they never return. Some species produce only one brood per year, but others may produce two or more.
Although pill bugs, like earthworms, are generally considered beneficial in gardens for their role in controlling pests, producing compost and overturning the soil, they have also been known to feed on cultivated plants, such as ripening strawberries and tender seedlings.
However, pill bugs can also invade homes en masse in search of moisture and their presence can indicate dampness problems. They are not generally regarded as a serious household pest as they do not spread disease and do not damage sound wood or structures.
I honestly thought pill bugs do not bring any benefits to the nature or environment but it was interesting to find that they play an important role as decomposer and enrich the soil.