Professional Herpetoculture for the Pet Trade

How To Breed Rosy Boas

Breeding Rosy Boas

One of the questions we get asked quite often is "Which type of snake is easiest to breed for a beginner". Our answer is always the Rosy Boa. The reasons for this are numerous, such as lack of need for incubators (they have living young) and the ease of getting neonates to feed and survive. This article will explain how we do it, using methods we've developed at VMS over the last twenty-plus years. Some articles may differ from the methodology presented here, and some may view it as overly simplified. Remember, Rosy Boas have been breeding in the wild for thousands of years without our help - they'll do it just fine in our cages, no need to make it harder than it is!

Do you really want to breed your Rosy Boa?

This seemingly simple question is often never considered by the novice. There are several reasons to consider NOT breeding your Rosy Boa!

First, do you have a market for the offspring once they have been produced? Rosy Boas have a distinct advantage in this area for beginners, they tend to have rather small litters of young compared to many other snakes. Litters can range from four to twelve. If you don't have a place to sell them right away, you won't get so tired of caring for them until disposed of.

Second, are you willing to risk the life of your Rosy? Breeding Rosy Boas is not without risks. On very rare occasions, one snake may actually simply eat the other on introduction. Dystocia (commonly known as egg-binding) is fairly common and poses serious health risks that may require expensive veterinary services. More common is the incredible drain on body resources that egg production places on the female. If not in perfect health, a female can become severely weakened and may succumb to renal failure or disease. Speaking of disease, the simple act of introducing the two snakes together opens the door for pathogen transfer. It is not uncommon for snakes to carry substantial parasite and bacteria loads and appear perfectly healthy, even for years. Introducing such a snake to another may transfer pathogens the second snake is unable to combat; it may then sicken and die.

I'm not trying to tell you not to breed your Rosy Boas, just making sure you are aware of a few of the problems associated with it. If you still want to breed them, read on!

The Calender of Events

I'll try to present all of this information in the order it occurs, following the calendar, to enable the reader to grasp the entire cycle of events. Breeding Rosy Boas is not simply something you just do one day, it is an event which consumes an entire year. Rosies spend their entire lives in the wild preparing for this one annual event - you should spend just as much time on it as they do! Please remember that these dates are not set in stone, variations in cage temperatures and other conditions may cause your results to vary. However, the overall sequence of events will remain unaltered.


Our Rosy Boas are hibernating now (more properly termed brumating), having been placed there at the beginning of December, in preparation for next summer's breeding season. While it seems that very little is actually happening at this time, the careful observer will note that the snakes are still active, at least a little. They still crawl about a bit, often drinking water and some will even shed their skins during this time.

Pay careful attention to them during this time. Most areas have much drier climates during the winter months and dehydration can be a problem. We make sure they have clean drinking water available at all times and check for 'dry shed' often. Many times, the snakes can be seen soaking in the water bowls when the climate is too dry - it's too cold for that! Take them out of the water and show them to their hide boxes.

We maintain our colonies at a temperature of 50-55 degrees Fahrenheit throughout the brumation period. We also greatly reduce the amount of light available to them. While not completely dark, there are no bright light sources at all. We maintain these cold temperatures by utilizing a thermostat which controls exhaust fans mounted in the ceiling. When activated, these fans remove warm air near the ceiling and cooler air from outside is simultaneously sucked into the room via air intake ducts. Temperatures are checked several times daily and the thermostat is adjusted adjusted slightly until the room is fully cooled, at which time the temperature is surprisingly stable. It is also recommended that air circulation be provided by using a fan. You would be surprised at how warm one end of the room can be while the other gets too cold!

For most keepers, this sort of system is impractical. We used to maintain these cold temperatures and light conditions by opening an outside window slightly, and covering the window completely with a dark sheet. Temperatures are checked several times daily and adjusted by opening or closing the window slightly. This served us well for many years!


Still chillin'. While this brumation all seems boring, it provides a bit of rest to the breeder, and more importantly to the snakes. Remember that egg follicles are developing and spermatogenesis is occurring in the males as well. It's important to maintain good conditions during this time so that all goes smoothly or infertile eggs will surely be the result.


Oh boy, now the work starts! We usually warm our snakes back up at the beginning of March. While many breeders advocate doing this by gradually warming them over a period of a couple weeks, we now know this is unnecessary. Instead we simply kick on the lights and turn back on the heat. Usually it takes a day or two to get all warmed back up. We believe, as do others, that maintaining snakes at those in-between temperatures can allow bacteria and other diseases which have lain dormant to activate and begin reproducing while the snakes immune systems are too cool to do anything about it.

We immediately check each specimen for any signs of disease and verify that they are strong enough and well-conditioned for breeding. We also use this time to select which males will be placed with which females to produce the desired offspring. We feed heavily during this time, after allowing the snakes a week to warm up to the idea. We find it best to feed small meals at first, gradually increasing to full-sized meals by the end of March.

Usually, the males will all shed their skins around the end of March, although this varies a bit. Make a note of this, as it serves to signify he is ready for breeding.


We are now feeding very heavily, and our work load is becoming tremendous, with hundreds of hungry mouths to feed and even more cage cleaning to do. Averaging a month later than the males, most of the females will now shed their skins for the first time of the year, although some may delay this until May. Occasional females will have shed almost immediately after warming up and will now shed again during this period, making it their second shed. It's not really important whether it's the first or second, the point is that it happens around this time - and this is the indicator that the female is ready for introductions to the male.

Many males will be seen to be restless, wandering around the cages endlessly - they can smell all those females nearby! Some males may refuse food during this period. Not to worry, they'll start feeding again once all the females have become gravid.

Figure 1: a pair of courting Rosy Boas

Whether the female has shed or not, we begin introducing her to the males' cage in mid-April. You can do it the other way around, it doesn't seem to matter, we just like to place the female in with the male.

If all is well, the male will show interest immediately, often pausing to smell the female as she glides by. Once he has determined that she is full of developing ova, his interest will quickly grow and he will begin to attempt to crawl on top of the female. The male may spend a lot of time trying to align himself on top of the female as shown here (Fig. 1).

Male Rosies can breed at ridiculously young ages and small sizes, and it can be pretty comical to see a tiny young male delicately perched atop a three foot long and very heavy female! You can see he is trying to get her to lift her tail section a bit by forcing his tail under hers, while stimulating her by scratching lightly with his vestigial spurs.

Figure 2: 'chin-rubbing' in courting Rosy Boas

The male will stimulate the female by rubbing his chin along her back and sides, or maybe it stimulates him - nobody knows for sure! (Fig. 2)

Figure 3: a pair of copulating Rosy Boas

If all goes well with this attempt, another look in a few minutes will reveal a successful copulation in progress. While this photo (Fig. 3) shows a pair still courting, copulations look very very similar. The main difference is that the male's tail can be seen wrapped underneath that of the female, rather than alongside as shown here. We'll continue introducing the pair together for periods of a day or two about twice per week, for the next couple of months, or until the female becomes visibly gravid. Many keepers simply keep their pairs together, separating them only to feed.


Virtually all our pairs are being introduced now, and many females are starting to show signs of ovulation at this time. Determining whether a female is ovulating can be difficult, but here's a few hints:

The first clue is a general heaviness throughout the lower half of the snake. Many keepers describe this as the snake looking like it just took a heavy meal, yet none has been given! Often, females will become aggressive at this time. Others may refuse food. (Yes, we feed throughout the breeding season if the snakes will accept it). Ovulating snakes will feel oddly firm at this time, almost as if they've suddenly grown muscular in the midsection. The main distinction is that this happens fast, with the snake appearing as usual one day and suddenly very firm and heavy the next. So paying constant attention to the females is required to recognize ovulation easily.

June - July

While a few of our Rosy Boas are still being introduced for mating, the majority of females are obviously carrying young now. They can be seen seeking out the warm spots on the floor of the cage, and most feed ravenously! Gravid females can achieve astonishing dimensions, often appearing so fat and round that they seem ready to split open! This heavy body weight makes motion difficult for them, and disturbances should be held to a minimum. Once we see the snake is obviously gravid, we cease introducing the male to her.

August - September

A second (or sometimes it's the third) shed of the year can be an indicator that the female is near to giving birth. Often, she will become restless, as if searching for a place to have her babies. Well, she is - so be sure to check the cage daily! Usually ours give birth in the very early morning hours, and the whole process takes about an hour. Following birthing, females will often eat any unfertilized ova which are produced.

Figure 4: newborn Rosy Boas

If all has gone well, you should one day look in the cage and see something like this:

Baby Rosies are born inside a thin membranous sack, and strong healthy babies will have no trouble piercing and escaping from the sack. In fact, most of the babies you will find will have already done so and quickly hidden underneath decorations or cage bedding. Babies which fail to emerge are usually premature, deformed or very weak. While it can pay to mess with these specimens to see if they'll get going, we usually just euthanize them to keep our lines strong and free of potential defects.

Usually the female will shed again within a week or two of giving birth and this is the real beginning of what I call 'the fattening'. Following this shed, until ready to enter brumation, female Rosy Boas will consume an astonishing amount of food. While our males will be on a maintenance diet of perhaps one feeding every other week, the females will be getting a small meal every five to seven days! They've earned it, as many have produced large healthy babies for for us.

If your snake has birthed earlier in the year, by all means start fattening her up earlier - don't wait!


Many females will have already regained a nice plump appearance during October. Those that are not regaining weight well, are marked and carefully observed for any problems which may require veterinary attention. Such snakes are marked and unless a sudden change for the better occurs, will not be bred the following season.


Now we are preparing for the upcoming return to brumation - and looking forward to a little rest! I'm sure the snakes are looking forward to it too! We feed all of them, male and female alike, heavily for the first two weeks of November, and then cease all feeding for the last two weeks. This allows time for the snakes to fully digest all meals, clearing out their digestive tracts before entering brumation. Snakes with digestive tracts containing undigested food will certainly encounter health problems if cooled.


All of our Rosy Boas are returned to winter brumation conditions sometime during the first week of December. Pay careful attention to them during the first few weeks. It often takes a day or two for the room to cool, and prowling specimens may tip over water bowls or spend excessive amounts of time soaking in the water dish. Snakes which soak excessively or are kept damp at this time have an increased potential for health problems. We usually remove the water dish and provide a very secure hiding place for such snakes. Once they've found the hiding place to their liking, the water dish may be returned to the cage.

Now that the snakes are all cooled down, we can take a break, look around at the scenery, and maybe even get caught up on all those unfinished projects around the house. Now that I stop to listen, Christmas songs are playing on the radio! I better get out and get some presents for friends and family - I know my Rosy Boas will give me more presents next summer!