Quick answer
The German cockroach (Blattella germanica) is a small, light-brown cockroach about half an inch long, marked by two dark stripes behind its head, that lives and breeds almost entirely indoors near kitchens and bathrooms.
It is the most common roach in U.S. homes, apartments and restaurants, and the fastest to multiply. Females carry their egg case until it is ready to hatch.
Quick facts
The key facts about German Cockroach, with sources:
Key takeaways
- German cockroaches are the small, tan roaches with two dark stripes that you find in kitchens and bathrooms.
- They live their whole lives indoors and depend on people for warmth, food and water.
- A female carries her egg case with her, which protects the eggs from many treatments.
- Many populations resist common insecticides, and some females refuse sugary baits because glucose tastes bitter to them.
- Sticky traps, sanitation and well-placed baits beat sprays and bug bombs.
What a German cockroach is
The German cockroach is the small roach that scatters when you turn on the kitchen light at night, an adult about half an inch long and light brown to tan.
Its clearest mark is a pair of dark stripes on the shield behind the head, called the pronotum 4.
Young roaches, called nymphs, are darker and nearly black, with no wings and a pale stripe down the back 4.
Despite the name, the species did not come from Germany: NC State researchers report that it arose in Asia about 2,100 years ago and spread with people, although the first scientific record comes from central Europe, about 250 years ago 1.
German roaches depend fully on people. Cold is the main limit on where they can live, and in northern areas they cannot survive in buildings without heat 4. That is why you almost never find them breeding outdoors, and why they travel with us in boxes, bags and appliances.
German vs Asian cockroach
The Asian cockroach (Blattella asahinai) looks almost the same but lives outdoors and flies toward lights. UF/IFAS says only a practiced eye can tell them apart 4. A roach indoors in the kitchen is far more likely to be German.
How a German cockroach population grows
Speed is the German roach’s main advantage, as one generation traced with NC State timings shows.
- Egg case forms: A mated female makes an ootheca about 8 mm long, holding about 40 eggs on average 1.
- She carries it: Unlike most roaches, she keeps the case attached until just before it hatches, moving to warm, safe spots 1.
- Eggs incubate for 20 to 30 days 1.
- Nymphs grow through five or six molts over 40 to 60 days 1.
- Adults breed: Females can reproduce 4 to 6 days after becoming adults. Each makes 5 to 8 egg cases, or 200 to 250 eggs, in her life 1.
- Egg case20–30 days incubation, carried by the female
- Nymph5–6 molts over 40–60 days
- Young adultFemale mature in 4–6 days
- Breeding female5–8 egg cases in a lifetime of 140–280 days
- Back to step 1
At room temperature the full loop takes about 70 to 100 days. Source: [1]
Life stages and how to recognize each
| Stage | What it looks like | Why it matters |
|---|---|---|
| Egg case | Light brown capsule, about 8 × 3 mm, often still attached to the female 4 | Shields eggs from many sprays; a female with a case is about to add dozens of nymphs 1 |
| Young nymph | About 3 mm, dark, wingless 14 | A sign of breeding on site, not a stray |
| Older nymph | Up to about 12.5 mm, still wingless 1 | In growing groups, about 80% of roaches are nymphs 4 |
| Adult male | Slender, tapered body, tip of abdomen visible 4 | Lives about 90–140 days 1 |
| Adult female | Stouter, rounded abdomen covered by wings 4 | Lives about 140–280 days 1 |
Worked example: why one female matters
This example walks through the published figures for a single female. It shows the scale of the problem, not a forecast for your home.
| Step | Figure | Source |
|---|---|---|
| Eggs per case | About 40 on average | NC State 1 |
| Cases in her life | 5 to 8 | NC State 1 |
| Her own lifetime eggs | 200 to 250 | NC State 1 |
| Generations in a year | About two at room temperature in Penn State’s estimate | Penn State 5 |
| Descendants in a year | Over 10,000 (Penn State); over 30,000 under ideal conditions (UC IPM) | 57 |
The two totals differ because they assume different conditions. Either way, a few roaches carried in on a box can become a building-wide problem within months.
Where you find German roaches and their signs
- Kitchens: Near dishwashers, stoves, sinks and refrigerators, where warmth and water meet 5.
- Bathrooms: Under vanities and around pipe holes 5.
- Inside things: Cracks in cabinets, hollow chair legs, light fixtures and appliance motors 5.
- Droppings: Small dark specks, like ground pepper, along hinges and shelf edges 7.
- Smell: Heavy populations leave an oily, musty odor 5.
- On paperwork: Inspection reports and invoices name “German cockroach” or “B. germanica,” the number of bait placements and trap counts. Our page on what a pest inspection covers explains how to read those reports.
Habits you can use against them
German roaches cluster, because more than 40 chemical cues in their droppings pull others to the same spots 1. Clustering makes them easier to find with traps and easier to target with small bait spots.
Poison also spreads between them. When roaches eat a roach killed by bait, they can die too, a domino effect NC State says baiting programs rely on 1. A good bait program uses this to reach roaches that never touch the bait directly.
Water is the third weak point, since fixing a dripping trap under a sink takes away something they cannot live without for more than a few days, and a dry kitchen pushes them toward baits.
Why German cockroaches are hard to control
Their strengths
- Resistance to every class of insecticide used against them since the 1950s has been recorded 2.
- Some females taste glucose as bitter and leave sugary baits, a trait called glucose aversion 3.
- Egg cases ride with the female, away from treated surfaces 1.
- They hide in narrow cracks deep inside cabinets and appliances 5.
What that means for you
- Over-the-counter sprays often fail or scatter roaches 5.
- Pros rotate insecticide modes of action at least every 3–4 months 2. See pesticide resistance.
- Baits made with glucose-containing sugars can be ignored; bait makers have moved away from them 3.
- Follow-up visits are normal, because a second hatch follows the first treatment.
What drives the cost of German cockroach control
The biggest cost drivers are the size of the population, the number of rooms or units involved and the follow-ups the plan includes. NC State notes heavy infestations may need a second bait visit about a week later 2.
Apartments and restaurants cost more to treat properly because nearby units must be inspected too, and clutter adds labor. Resistance can also add cost if the first products fail and the company must rotate. Read the cost guide and ask what is included before you sign.
A treatment has no fixed lifespan: results last as long as the causes stay fixed and new roaches do not arrive in boxes or from next door.
How professionals treat German cockroaches
A good company works through IPM steps in this order.
- Survey: Sticky traps at ten or more sites for about a week show where roaches gather 5.
- Clean up: Food sealed, dishes done nightly, trash lidded, sink strainers emptied 2.
- Bait: Many small, pea-sized gel bait spots in cracks near harborage 2.
- Dust voids: Light dust in wall voids and behind outlets where label allows; heavy deposits can repel 5.
- Seal: In apartments, caulk pipe and wall gaps after dusting 2.
- Re-check: Compare trap counts and adjust baits; switch bait base if roaches avoid it 2.
Many plans also use an insect growth regulator, a product that stops nymphs from maturing. Ask which products will be used and request copies of the labels.
Keeping German roaches gone
- Do not leave dishes, pet food or open food out overnight 5.
- Store dry goods in airtight containers 5.
- Keep monitoring traps under the sink, behind the fridge and in the bathroom; replace them when dusty or full 2.
- Inspect grocery bags, boxes and used appliances before bringing them in 5.
- Tell your landlord early in an apartment; delays let roaches spread through walls 1.
Health risks and signs you need a professional
German roaches produce strong allergens. NC State says one female can make up to 1,000 units of the allergen Bla g 1 a day, and that removing the infestation greatly lowers allergen levels and can reduce asthma 1.
A national housing survey found this allergen in about 63% of U.S. homes, mostly from German roaches 8.
They can also carry germs such as Salmonella on their bodies 1, and UC IPM lists Staphylococcus, Streptococcus and coliform bacteria 7.
Warning signs that call for a professional: roaches out in daylight, nymphs of several sizes, droppings in many cabinets, or a household member with asthma or allergies.
Do not mix or overuse products
Using several sprays at once can repel roaches from baits and expose your family. Follow the label exactly, and if someone swallows a product or reacts to it, call Poison Help at 1-800-222-1222, or 911 for trouble breathing 9.
Rules that govern German cockroach treatment
Every product used must be registered by the U.S. EPA under FIFRA, and its label is legally binding. A gel bait labeled for cracks and crevices may not be smeared on open counters. See how to read a pesticide label.
EPA guidance on total release foggers says they are flammable, must be kept at least six feet from ignition sources and are never for cabinets or closets 9. For German roaches, Penn State adds that they have little value anyway 5.
Companies treating for pay must hold the state license and category their state requires. Some cities also set landlord duties for pests in rental housing; check your local code. Our pesticide safety guide covers what to ask a technician.
German cockroach vs other common roaches
| Trait | German | American | Brownbanded |
|---|---|---|---|
| Adult size | About 1/2 inch 7 | About 1 1/2–2 inches 76 | About 1/2 inch 7 |
| Markings | Two dark stripes behind head 4 | Pale yellow band around the pronotum 6 | Light bands across the wings and body 7 |
| Lives | Indoors, kitchens and baths 7 | Sewers, drains, basements 7 | Indoors, warm and dry spots 7 |
| Egg case | Carried until hatch 1 | Dropped after about 6 days 7 | Glued in hidden spots 7 |
More on the large outdoor species is on the American cockroach page.
Myths about German cockroaches
- Myth They came from Germany.
- Reality NC State reports they evolved in Asia and spread with human travel 1.
- Myth A bug bomb will clear the kitchen.
- Reality Penn State says foggers have little value against German roaches and scatter them 5.
- Myth Roach baits always work.
- Reality Some populations avoid glucose-containing baits; the bait base must change 3.
- Myth They will die off in winter.
- Reality Indoors they breed all year in heated homes 4.
- Myth Killing the adults ends it.
- Reality Females carry egg cases that hatch later, so follow-up is needed 1.
How climate and housing type affect German roaches
German roaches do not follow outdoor climate the way other pests do, because they live inside. UF/IFAS says cold limits their survival, and in northern regions they cannot survive in buildings without central heat 4.
Housing type matters more than region: in the national allergen survey, 37.3% of high-rise apartments (five floors or more) had living-room allergen above the 8.0 U/g asthma-risk level 8. Licensing categories for companies that treat them vary by state.
When it matters to you, and what to do next
One small striped roach calls for sticky traps for a week and a cleanup of food and water. If the traps catch more, or you see nymphs or roaches by day, call a licensed company rather than starting with a fogger.
Ask the company to name the species, show trap counts before and after, and explain how they handle bait avoidance and resistance. Our cockroach treatment page lists what a complete plan includes, and how to choose a company covers the questions to ask.
Quick decision guide
One roach: trap and clean. Several roaches, nymphs or daylight sightings: call a licensed pro. In an apartment, notify management so nearby units are checked.
Questions about German Cockroach
How do I know if I have German cockroaches?
Small, tan roaches about half an inch long with two dark stripes behind the head are the giveaway. They gather in kitchens and bathrooms near warmth and water.
Other signs are pepper-like droppings, shed skins, egg cases and a musty smell. Sticky traps under the sink and behind the refrigerator will confirm them within a few days.
Where do German cockroaches come from?
German cockroaches usually arrive in grocery bags, cardboard boxes, used appliances, furniture or luggage. In apartments they also walk through shared walls and pipe gaps from nearby units. They do not live outdoors in most of the U.S., so an indoor infestation almost always started from something carried in or a neighbor.
Do German cockroaches fly?
No, German cockroaches have wings but do not fly. They run fast and may flutter when dropping from a height, but a similar roach that flies toward porch lights at dusk is more likely the Asian cockroach, which lives outdoors in the Southeast and looks almost the same.
How long do German cockroaches live?
Adult German cockroach females live about 140 to 280 days and males about 90 to 140 days, per NC State Extension. The full trip from egg to adult takes 70 to 100 days. Penn State gives a female adult life of 20 to 30 weeks, and temperature and food shift all of these numbers.
Why are German cockroaches so hard to kill?
They breed fast, hide deep in cracks and often resist the insecticides sold in stores. NC State says resistance has been recorded to every insecticide class used against them since the 1950s. Some also avoid baits that contain glucose, which they taste as bitter. Females carry egg cases until hatching, so eggs escape many treatments.
What is the best way to get rid of German cockroaches?
The most reliable approach combines sanitation, sticky-trap monitoring and baits placed in many small spots in cracks. Penn State says sprays and foggers have little value and can scatter roaches. Licensed pros rotate bait types and products to manage resistance. Heavy or apartment infestations usually need a professional with follow-up visits.
Can German cockroaches make you sick?
They can, mainly through allergies and asthma. Their droppings and shed skins carry allergens such as Bla g 1, and NC State says removing the infestation can reduce asthma.
They can also carry germs like Salmonella onto food and surfaces. If someone at home has worsening asthma, talk to a doctor and address the roaches quickly.
Do German cockroaches bite?
Rarely. UF/IFAS notes German cockroaches biting people only in extremely heavy infestations. The real health concerns are allergens and germs spread on food and surfaces, so unexplained bites point to a different pest such as bed bugs or fleas.
What does glucose aversion mean for roach baits?
Glucose aversion means some German cockroaches taste glucose as bitter and refuse baits that contain it. NC State research found their saliva even breaks down other sugars into glucose, so baits with sucrose or maltose can fail too. Professionals switch to baits with a different base when roaches stop feeding.
Sources
- NC State Extension, Biology and Behavior of the German Cockroach, retrieved .
- NC State Extension, German Cockroach Surveillance and Management (2025), retrieved .
- NC State University News, Sugar Aversion Hampers Cockroach Coupling (May 2022), retrieved .
- University of Florida IFAS, German Cockroach, Blattella germanica (EENY-002/IN128), retrieved .
- Penn State Extension, German Cockroaches, retrieved .
- Penn State Extension, American Cockroaches, retrieved .
- UC Statewide IPM Program, Pest Notes: Cockroaches (Publication 7467), retrieved .
- Cohn et al., National Prevalence and Exposure Risk for Cockroach Allergen in U.S. Households, Environmental Health Perspectives, retrieved .
- U.S. EPA, Safety Precautions for Total Release Foggers, retrieved .
Expert review
Written by the HyrePest Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Life-cycle timings, nymph sizes, behavior and allergen output follow NC State Extension; identification follows UF/IFAS; control steps and fogger findings follow Penn State and NC State Extension. Where Penn State and UC IPM give different population totals, both are shown with their source.
Suggest a correction. We fix errors and say what changed.