Why is this the answer?

The answer is fleas because this clever little riddle is talking all about a tiny, jumpy insect that loves to live on our furry friends, like dogs and cats. It is a puzzle that describes exactly what happens when you find one of these little creatures and what happens when you do not. Let us look at the first part of the riddle, "When they are caught, they are thrown away." A flea is a very small, dark, fast-moving bug that can jump super high. They like to hide deep in the fur of dogs and cats. If a pet has fleas, a grown-up will often use a special tool called a flea comb. This comb has tiny, close-together teeth that catch the fleas right out of the fur. Once a flea is caught on the comb, people do not keep it. They carefully throw it away right into the trash or a container of soapy water because these bugs are not safe or clean for the pet. They are definitely bugs no one wants to keep around. Now let us think about the second clue, "When they escape, you itch all day." If these tiny bugs are not caught and thrown away, they stay on the pet and continue to multiply. Fleas are pests because they have tiny mouths that bite the skin of the animal to drink a little bit of blood. When a flea bites a dog, a cat, or even a person, it leaves behind a little spot on the skin that feels very itchy and makes you want to scratch. If lots of fleas are escaping the comb or a bath, they will keep biting, and that means the poor pet, and sometimes even the people in the house, will be scratching and feeling uncomfortable all day long. So, the tiny insect you catch and throw away is a flea, and the itchiness you get when they are running free is from their little bites. It is a perfect match for the riddle's clever clues!