Dwarf Orange Bulborb

The Dwarf Orange Bulborb is an enemy in, , and. They are actually members of the Breadbug family, who mimic the Orange Bulborb to escape predation. Just like the Bulborbs they copy, they are very perceptive, noticing Pikmin at a greater distance than other Dwarf Bulborbs. Despite this, they pose a minimal threat, as they can still be quickly killed by either swarming or throwing Pikmin on their backs.

Pikmin 2 Nintendo Player's Guide
"Found in underground areas only, Dwarf Orange Bulborbs are little eating machines, and they're never far from an orange Bulborb. If you can separate the creatures, you can swarm them or stomp them fairly easily-but if you have to take them on in groups, you'll be in for quite a battle."

Pikmin 3 Prima Guide
"''Dwarf Orange Bulborbs aren’t nearly as durable as their as their fully grown counterparts. Toss a single Pikmin onto a Dwarf Bulborb’s back  to quickly defeat this enemy.''"

Pikmin
If a lot of Pikmin are available, swarm it and it should die before eating any Pikmin. Alternatively, aim and throw a bunch of Pikmin at its back. If one lands directly on it, it'll die right away. Purple Pikmin are especially useful for this technique, because they tend to home in on targets. In Pikmin 4, a direct hit with a Pikmin will not instantly kill the creature, and will rather deal two thirds of the beast's total Health.

In Pikmin 3, because of the lock-on mechanic, you can keep a moderate distance, wait until the enemy is idling in place, lock-on, and throw a single Pikmin for an easy kill.

Leaders
Run around it and swat it until it's dead, avoiding its attacks.

Trivia

 * The Dwarf Orange Bulborb differs quite a bit from the creature it's mimicking in Pikmin 2, having the orange on its body reach much farther frontwards, having brown fangs compared to the Orange Bulborb's white fangs, and having brown sclera compared to the Orange Bulborb's black sclera.
 * In Pikmin 2, like the other Bulborb-mimicking Breadbugs, if this creature is petrified in the Piklopedia, when it breaks out of the stone it runs around eating any thrown Pikpik carrots at a much greater speed than normal.