They hatch the eggs of vipers and spin a spider's web. Whoever eats their eggs will die, and when one is broken, an adder is hatched.
NIV
They hatch adders' eggs and weave the spider's web; he who eats of their eggs dies, and [from an egg] which is crushed a viper breaks out [for their nature is ruinous, deadly, evil].
AMP
They hatch cockatrice' eggs, and weave the spider's web: he that eateth of their eggs dieth, and that which is crushed breaketh out into a viper.
KJV