Get as many Blue Pikmin to knock down the wall. Then, get about 80 to 90 Pikmin of any color (Red recommended) and shoot them up onto the nearby ledge. You now can do one of two things; confront the spider or distract the beetle while you Pikmin grab the canopy and take it back to the ship. The safest way is to confront the spider. After you kill the beetle, you can take the canopy back.