Why Are Big Roaches Suddenly Showing Up in Your House?

Which Big Roach Are You Seeing?

An American cockroach can reach roughly two inches long. Adults are reddish brown with a lighter yellowish area behind the head. In Louisiana, American cockroaches are especially common in sewer and drainage systems, although they also live in other dark, damp areas.

That makes a large roach around a bathtub, floor drain, utility area, or plumbing especially worth noting. American cockroaches can move through sewer and drainage systems. If the water trap in a seldom-used drain dries out, that drain can also provide a route into the home.

A smokey brown cockroach looks different. Adults are usually about 1 to 1½ inches long and are a more uniform dark brown or mahogany, without the lighter marking behind the head.

Smokey browns also favor different surroundings. They lose moisture easily and do best in humid, protected places. Outdoors, that includes mulch, tree holes, potted plants, areas beneath decks, and other damp shelter. Around homes, they can live in crawl spaces, attics, and wall voids.

They're also strong fliers and are attracted to light. A large, dark roach flying around an exterior light at night fits smokey brown behavior particularly well. Repeated activity around an attic or other upper part of the structure can be another clue, since smokey browns commonly use attics and wall voids.

Where you see a roach isn't enough to identify it on its own, but it can be useful when the location matches the insect's appearance.

Why Can Big Roaches Suddenly Show Up After Heavy Rain?

A sudden increase in smokey brown cockroaches after a period of heavy rain isn't just a coincidence.

Smokey browns normally spend much of their time in protected outdoor areas. LSU AgCenter notes that heavy rain can drive smokey brown cockroaches into homes in greater numbers, which can help explain why sightings suddenly pick up after significant rainfall.

American cockroaches present a different situation. Because Louisiana populations commonly live in sewer and drainage systems, a run of large reddish-brown roaches around bathrooms or drains points toward a different possible route than smokey browns coming from mulch, trees, or other protected areas around the home.

Both species are primarily active at night, so homeowners are more likely to encounter them after dark.

What looks like a problem that suddenly started indoors can be increased movement from roaches that were already living in or around the structure.

A Bathroom Sighting and an Attic Sighting Don't Tell the Same Story

Where the sightings are concentrated can help narrow the search.

If a large reddish-brown roach repeatedly turns up in a bathroom, laundry area, or near a floor drain, American cockroaches deserve a closer look. They are routinely found around bathtubs, floor drains, pipe chases, crawl spaces, and sewers.

A seldom-used drain can be another clue. Plumbing traps normally hold water that creates a barrier between the living space and the drain system. If that water evaporates, the dry drain can provide an entry route for cockroaches.

An attic is different.

Smokey brown cockroaches are well adapted to humid, protected spaces and are regularly found in attics, crawl spaces, wall voids, and similar areas. American cockroaches, by comparison, are rarely found in attics.

If large, dark roaches keep appearing around an attic access, upper wall, soffit area, or other location near the roof, let Anti-Pest know where you've been seeing them. That can help narrow down the source of the activity.

What Do Daytime Sightings Mean?

Both American and smokey brown cockroaches are primarily active at night.

Seeing one during the day does not automatically mean the house is heavily infested. A hiding place can be disturbed, and an individual roach can end up exposed.

Repeated daytime activity is harder to dismiss, especially when other evidence is showing up in the same area.

Cockroach droppings, shed skins, egg cases, or small nymphs around a consistent location suggest something different from an occasional adult that wandered inside.

The size of the roaches matters here too. Tiny roaches repeatedly showing up in a kitchen call for a different diagnosis than one or two large American or smokey brown cockroaches appearing around a bathroom, garage, crawl space, or attic.

For a closer look at their nighttime behavior, see where cockroaches hide during the day.

Why Can Another Big Roach Show Up Days Later?

Large-roach problems can be frustrating because the sightings are often intermittent.

You find one, then several days pass without anything. Another appears later, sometimes in a different part of the house.

That makes more sense when you consider where these species can live.

An American cockroach population associated with a sewer, crawl space, or another damp protected area does not have to be living in the bathroom where an individual roach appears. Likewise, smokey brown cockroaches can remain hidden in an attic, wall void, crawl space, tree hole, or other humid harborage while only occasional adults make it into the rooms you use.

A quiet few days indoors doesn't necessarily mean the activity has stopped in the areas where the roaches are living.

That's also why repeatedly killing the roach that made it into the living space doesn't answer the more important question: where are they coming from?

Stop Big Roaches From Becoming an Ongoing Problem

You don't have to figure out whether you're seeing an American cockroach or a smokey brown cockroach before calling Anti-Pest. Our quarterly pest control plan covers both.

We start by inspecting your home and property and treating the pest problem that's already there. From there, quarterly service provides ongoing protection around the exterior, including common areas where roaches can enter, with interior treatment as needed.

And the Pest Plan isn't just for roaches. It also covers a wide range of other common household pests, giving your home year-round protection instead of waiting for the next pest problem to show up.

Keep Big Roaches From Becoming a Regular Sighting

One large roach inside can be an occasional invader. When American or smokey brown cockroaches keep showing up, it's worth finding out what is supporting the activity and how they're getting into the house.

Anti-Pest has helped homeowners in Shreveport and Bossier City since 1950. If big roaches keep turning up in your home, contact Anti-Pest for a free quote.