Key takeaways
- There are more than 4,500 cockroach species, but only a handful, such as the German and American cockroach, are household pests.
- Roaches hide in cracks by day, and their droppings release an aggregation pheromone that pulls others to the same spot.
- A German cockroach egg case holds about 30 to 40 eggs; an American cockroach case holds about 16, but that female lives far longer.
- German cockroaches have shown resistance to 43 insecticide active ingredients, and some avoid the sugars used in baits.
In this article
- A Few Problem Species Among Thousands
- Where Cockroaches Hide: Life in the Cracks
- What Cockroaches Eat and Drink
- How Cockroaches Communicate
- How Cockroaches Reproduce
- Why Cockroaches Are So Resilient
- Why Cockroaches Matter for Your Health
- Using Their Habits Against Them
- When to Bring in a Professional
- Frequently Asked Questions
Cockroaches succeed in cities because they live where we do not look. They spend the day packed into warm, dark cracks near water, come out at night to eat almost anything, follow chemical signals to the best hiding spots and breed fast enough to outrun most quick fixes.
Understanding that hidden routine is the key to controlling them. Every habit described below, from where they rest to what they drink, points to a weakness you or a professional can use. This guide walks through how cockroaches live, find each other, reproduce and survive, with a South Florida focus.
A Few Problem Species Among Thousands
Cockroaches and people have shared living space for thousands of years. According to University of Kentucky urban entomologist Zach DeVries, there are more than 4,500 cockroach species, and only a handful cause problems for people. Outdoors, most roaches are decomposers. UF/IFAS notes that they feed on dead or dying plants and animals outdoors and are considered pests when they invade lawns and gardens or enter homes and other buildings.
In Florida, the common pest species fall into two lifestyles:
- Indoor roaches such as the German cockroach, which lives and breeds only around people, and the brown-banded cockroach.
- Outdoor (peridomestic) roaches such as the American, smokybrown, Australian and Florida woods cockroaches, the large species Floridians call palmetto bugs. They live in sewers, mulch, trees and attics and wander indoors.
DeVries points out that the outdoor species tend to be larger, while the smaller indoor species cause most of the health concerns. Our cockroach guide shows how to identify each one.
Where Cockroaches Hide: Life in the Cracks
Cockroaches avoid light and like to feel surfaces around them. UF/IFAS reports that adults can squeeze into cracks about 1/16 inch wide but prefer spaces around 3/8 inch, roughly the width of a pencil. Those are the gaps behind baseboards, under countertops, around pipes and inside appliances.
Each lifestyle has its favorite neighborhoods:
- German cockroaches: UF/IFAS notes that the highest concentration in a home is usually around the garbage can and the refrigerator. Cabinet hinges, dishwashers, microwaves and coffee makers are also prime spots.
- American cockroaches: These live mainly in basements, sewers, steam tunnels and drainage systems, and UF/IFAS has recorded more than 5,000 in a single sewer manhole. During the day they rest near water pipes and other moist spots.
- Other palmetto bugs: Mulch, leaf litter, woodpiles, tree holes, palm trees and attics.
South Florida suits them perfectly. Heat and humidity last all year, the rainy season from May through October soaks mulch and drains, and dense landscaping and storm drains surround almost every building.
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What Cockroaches Eat and Drink
Cockroaches are omnivores and opportunists. UF/IFAS describes German cockroaches eating table scraps, pet food and even book bindings, and American cockroaches preferring sweets but eating almost anything, including decaying organic matter. DeVries sums it up: cockroaches love any and all food.
Water is a different story. It is the one thing they cannot do without for long. UF/IFAS found that German cockroaches survive about 12 days with food but no water, compared with about 42 days with water but no food. That is why roaches cluster around sinks, dishwashers, refrigerator drip pans, AC lines and bathrooms, and why UF/IFAS notes that they come indoors during droughts looking for moisture.
How Cockroaches Communicate
Roaches are not just random wanderers. German cockroaches in particular live in groups, and they use chemistry to find each other. Their droppings contain an aggregation pheromone, a chemical signal that draws other cockroaches to the same warm, dark, humid hiding places. That is why one crack behind the stove may hold dozens of roaches while the cabinet next to it holds none.
This behavior has a practical side. UF/IFAS recommends scrubbing infested areas with hot, soapy water because it removes the feces that carry the pheromone, making the spot less attractive to new arrivals. It also explains why roaches tend to return to the same areas after a careless treatment.
How Cockroaches Reproduce
All cockroaches develop in three stages: egg, nymph and adult. Females lay eggs in a protective capsule called an ootheca, and nymphs molt several times as they grow. The two main pest species take very different approaches.
Source: UF/IFAS EDIS (IN128, IN298)
| German cockroach | American cockroach | |
|---|---|---|
| Adult size | About 1/2 inch (10-15 mm) | About 1 1/2 inches (4 cm) |
| Egg case | About 30-40 eggs, carried by the female until just before hatching | About 16 eggs, dropped or glued near food |
| Development | Nymphs mature in about 60 days; full life cycle about 100 days | Egg to adult averages about 600 days |
| Adult lifespan | Shorter; breeds continuously with overlapping generations | Roughly 400 more days as an adult |
| Lifetime output | Populations can grow exponentially | About 150 offspring per female |
| Typical population | About 80% nymphs, 20% adults | Large sewer populations, migrating into buildings |
Sources: UF/IFAS EDIS IN128 and IN298.
The German cockroach’s strategy explains why infestations explode. The female protects her eggs by carrying them, nymphs often hatch while the case is still attached, and generations overlap without pause. Because a growing population is mostly nymphs hiding in cracks, the adults you see are only a small part of it, which we explore in why cockroach sightings often mean a larger hidden infestation.
The American cockroach plays a longer game. UF/IFAS reports that a female produces about one egg case a month for ten months, and her young take six to twelve months to mature. Fewer eggs, but a long, steady supply of new roaches from sewers and drains.
Why Cockroaches Are So Resilient
Several traits combine to make cockroaches hard to control:
- Hiding and timing. They feed at night and stay deep in cracks during the day, so infestations often grow large before anyone notices.
- Protected eggs. German cockroach females carry their egg cases until just before hatching, so new nymphs keep appearing after a spray that only hit the adults.
- Insecticide resistance. The University of Nebraska-Lincoln’s cockroach control manual lists the German cockroach among the 20 most insecticide-resistant arthropods, with resistance to 43 active ingredients documented as of 2021.
- Bait aversion. The same manual reports that some German cockroaches have developed behavioral resistance to bait attractants such as glucose and fructose, so they avoid eating certain baits.
- Mobility. UF/IFAS notes that German cockroaches can ride in on infested grocery bags and that infestations move between apartments through plumbing in shared walls.
For a deeper look at these survival traits, see understanding the resilience and adaptability of cockroaches.
Why Cockroaches Matter for Your Health
UF/IFAS notes that cockroaches can spread diseases such as Salmonella, and that their feces, shed skins and body parts are allergens that can trigger rashes and allergic reactions and, rarely, severe asthma attacks. American cockroaches move from sewers to kitchens, and German cockroaches live right next to food, so both can contaminate surfaces and stored food.
Using Their Habits Against Them
Every part of the secret life above points to a control step. This is the logic behind integrated pest management (IPM), which Nebraska Extension describes as identify, monitor, prevent, act and keep monitoring.
| Cockroach habit | Weak point | What to do |
|---|---|---|
| Needs water daily | Dry kitchens and bathrooms | Fix leaks, wipe sinks dry, empty drip pans |
| Hides in tight cracks | Sealable gaps | Caulk around pipes, cabinets and baseboards |
| Follows pheromone trails | Cleanable hiding spots | Scrub droppings with hot, soapy water; vacuum |
| Eats almost anything | Removable food | Seal food and pet food, empty trash nightly |
| Breeds in cardboard | Clutter | Recycle boxes, store items in plastic bins |
| Moves in from outside | Entry points | Door sweeps, screens, drain covers, thin mulch |
| Resists sprays | Bait in harborage | Baits in cracks and stations, never sprayed over |
UF/IFAS calls baits the most highly recommended control method, because they are effective and targeted, and warns never to spray insecticide where bait has been placed. Monitoring with sticky traps shows whether the population is actually shrinking.
When to Bring in a Professional
Knowing how roaches live helps you prevent them, but an established population, especially German cockroaches in a condo or restaurant, usually needs a professional plan with follow-up. Signs include roaches in daylight, nymphs or egg cases, droppings in several rooms or roaches that keep returning after treatment.
Toro Pest Management has protected South Florida since 1969, and its technicians train at the TORO Institute with on-staff entomologists. A Toro inspection finds where roaches hide, breed and get in, identifies the species, and targets cracks, crevices, voids and outdoor harborage with products applied according to their labels, plus sealing and sanitation recommendations and follow-up visits. If you are dealing with small kitchen roaches, our German cockroach guide explains the plan; for palmetto bugs, see the American cockroach page.
Homeowners can keep protection going with Total Home Protection Gold 365 from Toro’s residential pest control program, an every-other-month service inside and outside the home, while restaurants, hotels and property managers can ask about commercial pest control. If the bugs come back, so will Toro, at no additional cost to you.
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305-594-4767Frequently Asked Questions
Where do cockroaches go during the day?
Why do cockroaches come out at night?
How long do cockroaches live?
Can cockroaches survive a nuclear explosion?
Do cockroaches live in groups or alone?
Sources
- 10 things you should know about cockroaches, University of Kentucky College of Agriculture, Food and Environment
- Cockroaches and Their Management, UF/IFAS Extension
- German Cockroach, Blattella germanica (Linnaeus) (Insecta: Blattodea: Blattellidae), UF/IFAS Extension
- American Cockroach, Periplaneta americana (Linnaeus) (Insecta: Blattodea: Blattidae), UF/IFAS Extension
- Cockroach Control Manual, University of Nebraska-Lincoln Extension
Educational content. This article is for general information about pests in South Florida and is not medical, legal or professional advice. If you have a bite, sting or allergic reaction, contact your doctor; in an emergency, call 911. Pest problems vary from home to home, so a licensed professional should inspect before treatment. When using any pesticide, always read and follow the product label.
