Cockroaches are one of the most common household pests. They are often seen crawling in kitchen sinks, backs of refrigerators, cabinets, and rubbish bins, which makes one wonder how quickly these insects reproduce.
What is the life cycle of a cockroach? Cockroaches develop through incomplete metamorphosis consisting of three life stages: egg, nymph, and adult. Female cockroaches produce multiple eggs at a time. Depending on the species, cockroaches can complete their life cycles from 100 to 600 days.
Cockroaches survive in almost all types of habitats. Outdoors, cockroaches are found around trees and woodpiles. Indoors, they prefer warm, dark, humid areas. In this article are various information about cockroaches and ways to get rid of them.
What Is the Maximum Lifespan of a Cockroach?
Different species have different life spans. Under favorable conditions, below are the maximum lifespans of adult cockroaches that are known to inhabit human dwellings:
|American cockroach |
|Australian cockroach |
|Oriental cockroach |
|Brown-banded cockroach |
|German cockroach |
Cockroaches’ Life Cycle | Stages
Cockroaches undergo three stages during their life cycle: egg, nymph, and adult.
Female cockroaches do not lay eggs individually. Instead, they will form egg cases called an ootheca. Depending on the species, ootheca may appear in various colors such as tan, dark brown, or reddish-brown. The length and the number of eggs inside an ootheca will also vary with species.
|Species||Egg case length||Number of eggs|
|American cockroach||0.31” to 0.39”|
(8 to 10 mm)
|Up to 16 eggs|
|Australian cockroach||Up to 0.43” (11 mm)||22-24 eggs|
|Oriental cockroach||0.39” to 0.47”|
(10 to 12 mm)
|Up to 16 eggs|
|Brown-banded cockroach||0.16” to 0.20”|
(4 to 5 mm)
|Up to 16 eggs|
|German cockroach||0.28” to 0.35”|
(7 to 9 mm)
|Up to 48 eggs|
Some species carry these egg cases and only deposit them shortly before the eggs hatch. In some cases, eggs may also hatch while the ootheca is attached to the female cockroach. Depending on the species, temperature, and humidity, the eggs of adult female cockroaches will hatch after more than one month.
|American cockroach||50-55 days|
|Australian cockroach||40 days|
|Oriental cockroach||60 days|
|Brown-banded cockroach||50-74 days|
|German cockroach||28-30 days|
After the eggs hatch, the cockroach nymphs emerge. Nymphs resemble adult cockroaches but are smaller and wingless. Cockroach nymphs undergo a series of molting as it develops, usually lasting for a few hours to a few days.
In this process, nymphs shed their skin and replace it with a new dark and hardened exoskeleton. The number of molting required to reach adulthood differs among species and between sexes of the same species.
Similarly, the number of nymphs produced varies with species. Under favorable conditions, below are the estimates of the number of primary offspring produced and the duration of the nymphal stage of some cockroaches that thrive indoors:
|Species||Primary offspring||Duration of Nymphal Stage|
|American cockroach||336||5-15 months|
|Australian cockroach||720||6-12 months|
|Oriental cockroach||240||12 months|
|Brown-banded cockroach||320||3-6 months|
|German cockroach||384||1.5-4 months|
Nymphs receive no parental care; hatchling roaches are left to fend for themselves. They are often found in the same place as the adults and actively forage for food and water.
After molting several times, cockroach nymphs will become adult cockroaches. The length of time to develop into an adult varies with the following:
- Availability of resources such as water and food, and
- The condition of the environment, specifically temperature and humidity
Adult female cockroaches can produce several egg cases in their lifetime, depending on the species:
|Species||Number of egg cases|
How Long Is the Life Cycle of a Cockroach?
Completion of life cycles of cockroaches varies upon species as described below:
|Species||Development from egg to adult|
|American cockroach||600 days|
|Australian cockroach||>1 year|
|Oriental cockroach||>1 year|
|Brown-banded cockroach||161 days|
|German cockroach||100 days|
How Quickly Do Cockroaches Multiply?
As mentioned in the previous section, the length of time at which cockroaches reach adulthood will vary depending on the species. Consequently, the reproductive rate of each species will also differ.
|Species||Primary Offspring||Completion of Life Cycle|
|American cockroach||336||600 days|
|Australian cockroach||720||>1 year|
|Oriental cockroach||240||>1 year|
|Brown-banded cockroach||320||161 days|
|German cockroach||384||100 days|
Since it takes only 100 days for the eggs to reach sexual maturity, German cockroaches are known to have the highest reproductive rate. A single adult female German cockroach can produce 4-8 ootheca cases in its lifetime with up to 48 eggs per ootheca, which is equivalent to more than 300 eggs.
If half of the nymphs are females, each of them can produce another 300 nymphs. Thus, it would constitute approximately 30,000 total offspring in only one year of infestation.
Where Do Cockroaches Lay Eggs?
Cockroaches deposit their egg capsules in sheltered locations where the environment is warm and humid. Eggs are often found deposited in cracks and crevices, backs of refrigerators, cabinets, under sinks and toilets, and rubbish bins.
What Kills Roaches and Their Eggs?
Since most species of cockroaches are well-adapted to living indoors, a single method is unlikely to eliminate their populations. The following are various methods that can be combined to get rid of cockroaches and their eggs:
Vacuuming is an effective method to get rid of cockroaches and egg cases, especially in areas that are hard to access. For instance, a narrow tube placed on the end of the vacuum host can remove cockroaches located in cracks and crevices.
However, it should be noted that vacuuming will not kill live cockroaches. Thus, the vacuum bag should be sealed tightly and disposed of immediately to prevent the cockroaches from escaping.
Vacuuming can eliminate not only adult cockroaches but also nymphs and egg cases, especially if the infestation is isolated in an area. In case of a large infestation, vacuuming can be used in combination with other control methods.
Sticky traps are primarily used to identify cockroach harborages and detect and monitor the extent of the infestation. However, in areas with a small infestation, trapping can serve as an effective control method.
Traps should be placed strategically near harborages and crawl spaces to intercept cockroaches as they travel to and from hiding and feeding areas. Monitor each trap periodically and replace them as needed.
There are several options for pesticide treatment of cockroaches.
As with other forms of baits, cockroach baits are made up of a combination of a toxicant and an attractant. Indoor bait formulations are available in liquid and gels placed in bait stations.
Most commercially available baits contain active ingredients such as fipronil, hydramethylnon, or abamectin. Bait stations should be placed in numerous locations where cockroaches harbor.
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Insecticidal dust can also aid in controlling cockroach infestation. The most commonly known products are boric acid and diatomaceous earth.
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Dust should only be applied lightly since excessive application may repel cockroaches. These products can be applied to closet shelves, ceiling light fixtures, in the cracks and crevices, and wall voids throughout the house.
Residual sprays are often used in conjunction with non-residual insecticidal sprays. Non-residual sprays are applied in harborage areas, forcing cockroaches to come out of their hiding places, which in turn exposes them to surfaces that have been treated previously with residual spray.
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The presence of several sizes of nymphs and oothecae is an indication of a well-established colony. In such cases, it would be necessary to seek the help of a pest management professional for a more effective strategy, especially with non-chemical pest control methods (vacuuming, caulking, trapping) or with low-impact insecticides such as baiting and flushing.
Tips on Combating Cockroaches
Prevention is the key to the successful control of cockroaches and any other household pest. To prevent infestation, the following preventive measures may be employed:
- Carefully inspect all the items (boxes, furniture, cabinets, etc.) being carried indoors.
- Seal cracks and crevices in kitchens, bathrooms, exterior doors, and windows.
- Fix leaking faucets, pipes, and drains.
- The presence of a single cockroach warrants monitoring, and more than one justifies baiting, as cockroaches produce egg cases containing numerous eggs.
- Regularly clean potential harborage areas such as under sinks, cabinets, and furniture, back of the refrigerator, and other shaded areas.
- Deprive cockroaches of food and water sources by keeping your home clean.
Cockroaches are one of the most persistent household pests as these insects have become well-adapted to living indoors. Depending on the species, cockroach infestation could grow exponentially in one year. As such, preventive measures should be carried out to minimize cockroach invasion.
In the case of existing infestation, several methods could be employed to kill adult and immature cockroaches, such as vacuuming, trapping, and the use of various chemical controls.
List of Sources
Jiang, S., Kaufman, P. E. (2021). Australian cockroach. University of Florida.
McCanless, K. (2021). Oriental cockroach. University of Florida.
Piper, G. L., Antonelli, A. L. (1997). Cockroaches: Identification, Biology, and Control. Pacific Northwest Extension.
Schofield, K., Keck, M. Creepy Crawly Cockroaches. Texas AgriLife Extension Service.