Answer:
A mighty weapon in the war against winged household pests.
What breaks on the water but never on the land?
If you drop me I'm sure to crack. But give me a smile and I'll always smile back.
What can be underwater, under fire, on fire and taking water all at the same time?
There are millions of me. I am very small but when moving fast I am deadly.
All about, but cannot be seen, Can be captured, cannot be held, No throat, but can be heard. Who am I?