Roof Rats in Citrus Neighborhoods: How They Get Into Attics and How to Keep Them Out

Roof rats get into attics in citrus neighborhoods by climbing the trees, hedges and utility lines that touch the house and entering at the roof line through unscreened vents, the gap where tile meets fascia and the hole where the AC line set enters the wall. Keeping them out means trapping the ones inside, sealing those entries with hardware cloth and copper mesh, and cutting the trees and hedges back off the house.

Why Roof Rats and Citrus Go Together

The roof rat (Rattus rattus) is a climber. It is slimmer than a Norway rat, with a tail longer than its body, and it lives above ground: in trees, hedges, palm skirts, attics and on utility lines. It arrived in the Phoenix area through the Arcadia neighborhood and spread across the Valley along the same features: mature citrus, oleander hedges, palms, flood irrigation and overhead lines. Any neighborhood in Phoenix, Mesa, Tempe, Chandler, Glendale or Scottsdale with 30 year old orange trees has them.

Citrus is food and shelter at once. Roof rats eat the fruit on the tree, leaving the hollowed out rind hanging, which is the classic sign. They nest in the dense canopy and in the skirt of dead fronds on an unpruned palm. An oleander hedge along a block wall is a covered runway from the yard to the roof. And a flood irrigated lawn keeps the whole yard green and full of the insects and seeds they also eat.

How They Get Into the Attic

Roof rats rarely enter at ground level. The route is up. They climb a citrus branch that touches the eave, walk an oleander that reaches the roof, run along the cable or power line to the house, or go straight up the stucco at a corner. At the roof line they use a handful of openings.

• Attic and gable vents with a rusted or missing screen, or a screen with mesh large enough for a rat, which needs only a half inch gap.

• The gap where tile roofing meets the fascia, an open channel along every eave on a tile roof unless it was bird stopped.

• The AC line set entry, where the refrigerant lines enter the wall through a hole packed with foam that crumbled years ago.

• Roof to wall junctions and dormers where flashing has lifted.

• Plumbing vent stacks and the chimney where the flashing has a gap.

Once inside they nest in the insulation, chew wiring, and run the same path every night, which is why the noise in the ceiling comes at the same time and in the same spot.

Signs You Have Them

Hollowed citrus on the tree or on the ground. Scratching or running sounds in the ceiling after dark, usually within an hour of sunset and again before dawn. Droppings in the attic, about a half inch long with pointed ends. Grease marks along a beam or at a vent where they rub. Chewed wiring or ducts in the attic. A dog that stares at the ceiling. Sometimes a rat on the block wall or the fence at dusk, moving along it like a tightrope.

Why Poison Alone Fails

Bait blocks on the patio or in the attic are the usual first move and the usual mistake. A poisoned roof rat dies where it feels safe, which is inside the wall or in the attic insulation, and the smell lasts 2 to 4 weeks. The bait did nothing about the gap it came through, so the next rat arrives a month later. And loose bait in a yard is a hazard to dogs, cats and owls. The order that works is trap, seal, then clean up.

How to Keep Them Out

1. Trap first. Snap traps in the attic along the runways, on the beams and near the entry, checked every day or two until a week passes with nothing caught. Traps let you remove the rat instead of leaving it in the wall.

1. Seal the roof line. Hardware cloth over every attic and gable vent, bird stop or sealant along the tile eave, copper mesh and sealant at the AC line set, flashing repaired at vents and chimneys. Expanding foam on its own is chewed through in days.

1. Cut the highways. Trim citrus and any tree so no branch is within 4 feet of the roof or walls, cut oleander down off the wall and away from the house, prune palm skirts, and remove ivy or vines on the walls.

1. Reduce the food. Pick fruit when it is ripe and pick up drops, clean the bird feeder area, keep pet food inside, and secure trash lids.

1. Bait stations only in locked boxes, along exterior walls where they add something, never loose.

1. Clean the attic with disinfectant on the droppings before removal, gloves and a mask, and replace soiled insulation if it is heavy.

Roof rats chew wiring, which is a fire risk in an attic, and their droppings and urine contaminate insulation and ductwork. They also carry fleas and can spread disease to pets. A colony in the attic is not a wait and see problem.

FAQ

Are these the same rats that chew car wiring? Usually not. Vehicle wiring damage in Arizona is mostly pack rats on desert edge lots. Roof rats are the citrus neighborhood attic rat.

Will cutting down my citrus fix it? No, and you do not need to. Trimming the tree off the house, picking the fruit and sealing the roof line does the job while keeping the tree.

How do I know they are gone? A week of empty traps after sealing, no new droppings on a paper laid in the attic, and quiet ceilings. A follow up check a month later confirms it.

If there is hollowed fruit on the tree and noise in the ceiling at night, a rodent control program from Green Ninja Pest Control traps the rats, seals the roof line and shows you which branches have to come off the house.