Ladybird, ladybird fly away home,
Your house is on fire and your children are gone,
All except one,
And her name is Ann,
And she hid under the frying pan.
Ladybird, ladybird, fly away home,
Your house is on fire,
Your children shall burn!
Ladybug, ladybug, fly away home.
Your house is on fire;
Your children all roam.
Except little Nan
Who sits in her pan
Weaving her laces as fast as she can.
It is a allusion to the custom of setting fires to smoke the bugs out of vegetation. It caused the ladybugs to fly away. The younger insects, in caterpillar form, would have to creep away. Therefore "your children all roam". The insects in pupate form, inside their shells, would not be able to escape the peril and therefore would die from the smoke or fire. The design is that Nan is inside her pupal container and cannot escape until she breaks free - "weaving her laces", undoing her pupal case.