He can't figure out why these bugs are heavy outside and inside

 causes of  insect, bug and pests including rodents, racoons, rats, snakes include

piling up things alongside the house, 

piles of tree pieces for firewood piled up close to back of the house

throwing rotten tomatoes and any other organic food items into the garden instead of tossing it out far away from the house like the end of the driveway close to the street