Rat Control in Delaware

What rats look like

The Norway rat (Rattus norvegicus) is heavy-bodied, with a blunt nose, small thick ears and coarse, grizzled brown-gray fur, paler underneath. Head and body run about 7 to 10 inches, and the tail is shorter than head and body combined - thick and scaly. An adult weighs ten to sixteen ounces, ten to twenty times a house mouse.

Rats are cautious and mostly nocturnal, so daylight sightings usually mean heavy pressure or a disturbed burrow. The evidence is more useful than the animal.

• Burrows. Openings two to four inches across with a fan of loose soil, set against a foundation, under a stoop or shed, or along a ditch bank. Active ones are clear of cobwebs and leaf litter.
• Runways. Beaten paths through grass or ivy, or smooth dust-free lines along a wall or joist. Rats reuse routes and follow edges.
• Droppings. Half an inch to three quarters, capsule shaped, blunt at the ends, usually in concentrations rather than evenly scattered.
• Gnaw damage. Coarse and large-scale - chewed door bottoms, enlarged utility openings, damaged plastic pipe and conduit.

How they get in

A Norway rat gets through a gap about half an inch across and will enlarge one that is too small. It is also a competent digger, so exclusion has to account for what is under the wall as well as what is in it.

• Broken, uncapped or dry-trapped sewer lines and floor drains. Norway rats travel sanitary sewers, and a failed line under a slab is an interior route with no visible exterior hole.
• Damaged crawlspace vent screen and access doors that no longer seat, a recurring route in the crawlspace foundations around Camden and Wyoming.
• Gaps under stoops, porches and slab edges, where a burrow reaches a void and then a penetration.
• Garage doors with worn bottom seal, and the corner gaps at each jamb.
• Farm and outbuilding openings - feed room doors, siding at grade, floor edges in equipment and grain buildings.

What draws them to a property

Rats settle where food, water and cover sit close together: chicken coops and spilled feed, pet food left out, unsecured trash, compost with kitchen scraps, ivy or woodpiles at grade, standing water in ditches. Construction and demolition also displaces established populations, which is why new-build activity around Middletown sometimes produces rat calls in new neighborhoods.

What they do

Rats do more structural damage than mice and carry a somewhat higher health risk, but the risk is worth stating in proportion rather than inflated.

Damage runs two ways. Above ground, gnawing takes out wiring, plastic water and gas lines, conduit and insulation. Below ground, burrowing is the bigger issue: sustained burrowing under a stoop, patio, shed slab or foundation edge removes support and produces settling and cracked pavers.

On health, rats contaminate stored food and surfaces with urine and droppings. Leptospirosis, carried in rat urine in standing water, is the exposure most worth knowing about, though cases here are uncommon. Bites are rare. Rats also carry ectoparasites, so a heavy problem can leave fleas behind once the rodents are gone.

When you see them in Delaware

Norway rats are active year-round here. Mild coastal winters along the Delaware Bay do not knock back outdoor populations, so the question is where they are living at a given time of year.

Autumn is when they push toward structures. Grain harvest through Felton and Harrington removes cover and concentrates feed while night temperatures drop, and rat calls climb through October and November alongside the first hard frost.

Winter activity is concentrated: burrows near a heat source or reliable food, movement at night along fixed runways. Rats already in a crawlspace or outbuilding tend to stay there through deep cold, which is when gnaw damage and noise complaints peak.

Spring warm-up in March and April brings breeding and dispersal, and new burrows appear along foundation lines and ditch banks. Through summer most activity is outdoors near dusk, which is the easiest time to census burrows and do exclusion work.

Norway rats vs roof rats and mice

Two comparisons matter, and one common assumption is worth correcting directly.

Roof rats are not established in Delaware

The roof rat (Rattus rattus) drives rodent work in the Gulf states and parts of the Southeast. It is not established in Delaware. Anyone describing roof rats here is almost certainly describing a Norway rat, or an animal in the attic that is not a rat at all - squirrels are the usual answer for daytime attic noise, and that is a job for wildlife removal.

For the record, a roof rat is slimmer, with large thin ears, a pointed muzzle and a tail longer than head and body. The behavioral difference is the practical one: roof rats work vertically and nest high, Norway rats burrow and work at or below grade. Treating one as the other sends the inspection to the wrong elevation.

Rats vs mice

Droppings settle it. Rat droppings are half an inch or more and blunt-ended; mouse droppings are under a quarter inch and pointed. A juvenile rat is easily mistaken for an adult mouse, but it has an oversized head, heavy hind feet and a thick tail base. If the evidence is small and fine, see our page on mice instead.

How to keep them out

Rat prevention is half habitat and half exclusion. Removing food and cover reduces how many rats a property can support; sealing decides whether they get inside.

• Remove harborage at grade - dense ivy against the foundation, woodpiles stacked on soil, junk piles and unused equipment sitting on the ground.
• Secure feed and waste. Chicken feed, birdseed and pet food belong in metal containers with fitted lids, coop spillage cleaned up daily, trash and compost in rigid containers with latching lids.
• Screen crawlspace and foundation vents with hardware cloth rather than window screen, and repair crawlspace doors so they seat.
• Seal openings with metal - sheet metal, hardware cloth or mortar. Rats chew through foam, wood and plastic patches.
• Address the ground. A buried hardware cloth apron at sheds, decks and stoops stops burrowing under an otherwise sealed structure.
• Fix drainage and standing water where practical. Wet ditch banks and damp low corners are burrow habitat.

Filling a burrow without dealing with the animals accomplishes little - rats reopen a plugged burrow within a night or two. Sequence matters: reduce first, then close.

How we treat rats

Rat work follows the same integrated pest management sequence as other rodents, with more weight on the exterior and on the ground.

Inspect and identify

We start with a burrow census and an exterior survey - foundation line, stoops and slab edges, sheds and outbuildings, ditch banks, trash and feed storage. Interior inspection covers the crawlspace, utility rooms and floor drains. Where interior activity has no visible exterior route, sewer lines get attention. Species and scale are confirmed from droppings, burrow size and damage before anything is placed.

Treat and monitor

Exterior work uses tamper-resistant stations placed on runways and near burrow entrances, sited away from areas used by children and pets. Interior work is trap-based. Because rats are cautious, equipment often sits untouched for days before it produces, so we plan around that rather than churning placements. Non-toxic monitoring blocks help early for confirming activity and mapping routes.

Exclude and follow up

Sealing with metal and hardware cloth is the durable part of the job, documented with locations. Follow-up inspection checks burrows against a marked baseline and verifies that sealed points held. Continuing coverage runs under rodent control. On a property backing onto farmland or a ditch line, no program removes the outside pressure permanently, and we would rather say so plainly - get in touch if you want it looked at.