If Resonance Insect is sent from the field to the Graveyard, it allows you to add a Level 5 or higher Insect-Type monster from your Deck to your hand. You can use Resonance Insect’s effect to search Mother Spider or Doom Dozer.
If you banish Resonance Insect from your Graveyard to activate Lair Wire or to Special Summon Doom Dozer, its second effect will trigger, allowing you to send another Insect-Type monster from your Deck to the Graveyard, ready for your next play.
If you only have Insect-Type monsters in your Graveyard, you can Special Summon Mother Spider from your hand by sending to the Graveyard two face-up Defense Position monsters on the opponent's side of the field. There has to be at least 1 Insect-Type monster in your Graveyard for you to Special Summon this card, but, since it's not stated otherwise, you can still Normal Summon it.
Compared to Reptilianne Vaskii, Mother Spider has a lot more restrictions when it comes to Summoning Conditions, but switching two monsters your opponent controls into Defense Position is definitely a lot easier than lowering their ATK to 0.
As you can probably already tell, the main appeal of this card is the fact that it allows to remove from the field two of your opponent's monsters:
If you send Silent Magician to the Graveyard in order to Special Summon Mother Spider, your opponent will not be able to Special Summon Silent Magician LV8 from their Deck or hand because the effect only triggers when the monster is destroyed.