No, they are peacful
Yes, but they only bite small bugs like aphids and scale bugs. They don't bite humans, don't think they have the mandibles to even accomplish such a task!
They eat aphids to live
Ladybugs are indeed helpful to humans, because they eat aphids, and aphids are damaging to many plants that we humans like to grow.
certain species of ants use aphids similar to how humans use cows: they lead them to graze and collect a liquid discharge the aphids excrete from their abdomen. ants also protect aphids from harm similarly to how humans keep their livestock safe from harm.
Dogs bite humans because they smell fear.
Yes a nice vampire might bite a humans
The nouns are: pest, humans, bite.
Yes, aphids bite people. Any insect with piercing, sucking mouthparts is capable of scratching skin surfaces just as they plant tissues. The experience will be more like getting a minor abrasion from a slightly rough surface than like having the skin broken by a bee, hornet, scorpion or wasp sting or a snake bite.
They don't bite humans.
Everything bites humans.
The two can both be herded and 'milked' . Cows are domesticated by humans whereas aphids are used by some ants for the sweet secretion that the aphid exudes .