So you’re considering a Dubia roach breeding project, and then it hits you: How many dubia roaches does it take to start a colony? How many will you need? You know you could conceivably do it with just 2 adult roaches, but this isn’t really what you’re asking. You want to know how many roaches you need to start with in order to end up where you imagine you want to be. This is a common question, and the answer isn’t as complex as it seems.
However, in addition to the natural growth rate of Dubia roaches, the answer for you also depends on you and your situation. For your answer to be meaningful, you must first determine your goals for the colony.
The following information will help you do both.
Colony growth is a function of time
Identifying your goals involves answering basic questions about your intended colony size and function. For example, do you want the colony to supply a steady stream of feeders? If so, how many and how often? Do you want a big colony without concern for feeders? If so, how big do you want it to be? And importantly, when do you want it to be that big? Is next year OK, or do you want it sooner?
The answer to the “How many roaches do I need…” question depends on you and what you want for the colony because there is no set number of Dubia roaches required to start a colony. In theory, you only need one pregnant female. Or you can start with a single male and a single female, or several of each, a dozen, a hundred, etc.
Obviously, how fast this potential colony grows and how soon it reaches the size you want is the real question. If you want a small colony of 10 adult roaches, you can start with just a few. However, if you want a colony of 10,000 within a reasonable time, you should start with more. But how many more, and in what time? These are the real questions at hand.
The first step toward finding an answer is determining your needs and expectations. From there, it’s easy to figure out the number of Dubia roaches you need to start a colony that will do what you want when you want. Determine your goal first. Then calculate a starting point with data about Dubia roach reproductive physiology. It’s sort of a reverse engineering approach to building a colony, if you will. The estimate is rough, but the numbers work. The rest is in the implementation.
Let’s start with the basics:
Dubia roach reproductive timeline
All things equal, newborn Dubia roaches reach adulthood in about 5 months. Newly-emerged males begin mating almost immediately, while newly-emerged females start about a week later. Females can become pregnant immediately upon mating, and their gestational cycle is 65 days. This means the earliest a female can give birth to a batch of nymphs is 72 days after the day she reaches adulthood. This is roughly 220 days after she is born.
We (roughly) estimate that females give birth to about 25 nymphs in the conditions commonly found in home Dubia roach colonies. The actual number may be more or less, but 25 is a reasonable average. They repeat this every 65 days.
Colony population estimate
So let’s say, for example, that you start a new colony on day 0 with 5 newly-emerged females and one male. You can expect 125 newborn nymphs in 2.5 months, then again every 65 days after that. Assuming a 75% survival rate and a 50/50 male-to-female ratio, the first nymphs born will begin giving birth at about 7.5 months. At that point, you will have about 50 adult females and 1,250 nymphs.
At 7.5 months, the population begins some pretty serious exponential growth. This is when the first batches of nymphs have babies of their own. This is a reasonable cut-off point. You will have a colony with many thousands of roaches whether you started with 10 adult females, 50, or even 100. In fact, if you can wait a year, this discussion is largely irrelevant. At that time, almost any starting number will yield thousands of roaches of all ages.
But this takes a year. You may decide a year is too long to wait to reach your population goal for the colony. What can you do if you don’t want to wait? How many females should you start with to have 1,000 nymphs in four months? How about three months? What if you don’t want to wait 7.5 months for the roaches to complete one reproductive life cycle and for the colony to become self-sustaining?
Estimates refined: the population graph
You’re in luck! We put together the following graph using the formulas and averages mentioned above. The data is based on the most accurate estimations of the Dubia roach life and reproductive cycles we could find. You can use it to estimate population start and endpoints. This means you can decide what you want your Dubia roach colony to be, use the information above to determine how many roaches it takes to be it, and then plot how many you need to start with to get there.
The data allows you to plot the nymph population as a function of the starting female population and time. You can figure out roughly how many nymphs you’ll have in a new colony at any given point in time between 0 and 200 days, given an initial starting female population of between one and maybe 60 or 70. Again, these are rough estimates. You can extrapolate the population based on higher starting numbers or more time, but as you can see, the population goes exponential. Actually, we removed some data (starting populations of 75 and 100) because the scale necessary to display such high numbers made the lower results impossible to read. However, it’s fair to extrapolate if that fits your situation.
NOTE: “Total population” is nymphs plus adult females, so just subtract the number of females from the total to get rough nymph numbers. If you know how many nymphs you want the colony to have at any given time, you can estimate the number of females you’ll need to start with to get there.
Summing it up…
So that’s basically it. Colony size as a function of starting female population and time. Or, work backwards to hit a population target. Simple. Sort of.
This should answer the question of how many Dubia roaches you need to start a colony. That said, please keep in mind that while these projections are based on actual data and Dubia roach physiology, your mileage may vary. Things can be very different in the real world. Many factors influence Dubia reproduction and colony population growth. They include temperature, food availability, crowding, stress, etc. We’ve written about these things in our Dubia Roach Breeding Guide, which we recommend reading if you’re interested. Learning about Dubia roach breeding is the logical next step in planning and implementing your new colony.
We’ve also written several other in-depth posts on related topics that might interest you, including one on maximizing the natural B. dubia growth rate and another on diagnosing and curing Dubia roach breeding troubles.
Have a question?
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