饿虎扑食 (èhǔpūshí) hungry tiger seizes prey (fierce and swift action)
But it's interesting to see how far goes the derivation of this original chengyu.
饿狼扑食
饿狮扑食
饿熊扑食
饿龙扑食
饿狗扑食
饿猫扑食
饿兔扑食
饿鼠扑食
饿鱼扑食
饿龟扑食
...
饿汉扑食
饿女扑食 -> 34,300 results on Google for "饿女扑食"

Btw, No results found on Google for "flexible Chengyu".  ;o)