龍蝨科

幼虫及其发育

When still in larval form, the beetles vary in size from about 1 to 5 cm (0.5 to 2.0 in). The larval bodies are shaped like crescents, with the tail long and covered with thin hairs. Six legs protrude from along the 胸, which also sports the same thin hairs. The head is flat and square, with a pair of long, large pincers. When hunting, they cling to grasses or pieces of wood along the bottom, and hold perfectly still until prey passes by, then they lunge, trapping their prey between their front legs and biting down with their pincers. Their usual prey includes 蝌蚪s and glassworms, among other smaller water-dwelling creatures.
As the larvae mature, they crawl from the water on the sturdy legs, and bury themselves in the mud for 蛹. After about a week, or longer in some species, they emerge from the mud as adults.

食用

本科物种的成虫，特别是Cybister属的物种，均为可食用昆虫。在美国内华达州洪堡干湖的一个山洞内，还在当地史前人类遗下的粪化石内发现有Cybister explanatus被食用的残骸。在墨西哥，他们在吃C. explanatus时会以墨西哥夹饼夹着来吃。在日本多个地区（例如：长野县）有以日本龙虱（Cybister japonicus）为食的习惯；在中华人民共和国广东省，除了日本龙虱以外，亦会食用C. bengalensis、C. guerini、C. limbatus、C. sugillatus、C. tripunctatus等物种。D. marginalis很可能也包括在内，但这个物种的肉很少。也有报告指在台湾、泰国及新几内亚亦有食用本科物种的习惯。
Large but slow on land and not particularly fierce as adults, they are also eaten with relish by many midsized 鸟s, 哺乳动物s, and other larger 捕食s. The larvae are usually safer, due to their 保护色 and ability to escape by water jet; they can be quite hard to catch and may become 顶级掠食者s in small 池塘s.

Cultural significance

The diving beetle plays a role in a 切罗基人 creation story. According to the narrative, upon finding nowhere to rest in the "liquid chaos" the beetle brought up soft mud from the bottom. This mud then spread out to form all of the land on Earth.

Ethnobiology

Adult Dytiscidae, as well as 豉甲科, are collected by young girls in 东非. It is believed that inducing the beetles to bite the nipples will stimulate breast growth.

寄生虫

螨 of the genus Dytiscacarus were found to be are highly specialised 寄生 of 鞘翅目 in the family Dytiscidae, undergoing their entire life cycle while inhabiting the space beneath the 翅鞘 of their hosts.