Ntau tus niam txiv muaj ntau xyoo ntawm kev ua tswv cuab dev, thiab cov dev hluas pib hloov lawv cov hniav thaum lawv muaj hnub nyoog 3-5 hli. Thaum hloov cov hniav, tus dev yuav hnov tias cov hniav mob thiab khaus, yog li lawv yuav nrhiav tau ib yam dab tsi los zom rau qhov tsis xis nyob. Tab sis tus dev tsis paub dab tsi tuaj yeem tom, nws tsuas yog xav tias nws lom zem rau tom cov ntawv xov xwm, xov tooj ntawm tes, thiab xov hlau.
