The reason Parasite Infestation is a good skill for a Doom Dozer deck is because once Parasite Paracide is sent to the graveyard he will be sent to your graveyard, so you can banish it for Doom Dozer.
The Doom Dozer deck is straightforward, you can stall a bit with Man-Eater Bug or Resonance Insect while also filling your graveyard with insects and adding Doom Dozer to your hand, once you have enough for game you can use Hey, Trunade to clear your opponent’s field, summon an insect monster, use Enemy Controller to take control of an opponent’s monster which means you add another insect to your graveyard and then you can special summon your Doom Dozers to attack for game.
Cannot be Normal Summoned or Set. Must be Special Summoned (from your hand) by banishing 2 Insect-Type monsters from your Graveyard, and cannot be Special Summoned by other ways. When this card inflicts Battle Damage to your opponent: Send the top card of their Deck to the Graveyard.
If this card is sent from the field to the Graveyard: You can add 1 Level 5 or higher Insect-Type monster from your Deck to your hand. If this card is banished: You can send 1 Insect-Type monster from your Deck to the Graveyard, except "Resonance Insect".