Sometimes the Sling Lottery Just Does Not Love You Back

My Unlucky Streak

This post was inspired by a recent streak of spiderlings that reached their ultimate molt and, one after another, turned out to be male. Somehow, it feels like I have been especially unlucky lately. I mean, statistically speaking, the chance of getting the desired sex when buying an unsexed tarantula sling is about 50 percent. Yet sometimes it really does not feel like that. I am fairly sure some cognitive bias is at play here, because losses tend to sting more than wins feel good.

Since I track every tarantula I own in a database and small web app that I built for myself, I actually have the numbers. Over the last three years, I bought 16 unsexed slings. Out of those, 9 turned out to be males. On top of that, one tarantula I bought at an invert expo here in Austria as a confirmed female eventually molted out into a mature male. That one hurt a little more. Because in addition to disappointment, I also felt betrayed.

If you run the numbers, 9 males out of 16 slings is not outrageous. Assuming a true 50 percent probability, the chance of ending up with 9 males or more is about 40 percent. That is not rare at all. It is well within what you would expect from a small dataset. Rationally, I know that. Emotionally, it still feels like the sling lottery is laughing at me.

What probably adds to that feeling is that out of the remaining seven tarantulas, only two are actually confirmed females via molt sexing (I explain that process in detail here). The others simply have not given me a sexable molt yet. So for now, the balance looks worse than it actually is.

I asked a mathematician how to deal with an unlucky streak. His solution was simple: buy infinitely many slings.

Why I Still Buy Slings

Despite this record, I will continue buying slings. Not because I enjoy disappointment, but because I genuinely believe it is the right approach for the hobby.

First, buying females only is not sustainable. I understand why everyone wants females. They live longer, they grow larger, and they feel like a safer investment. But if everyone only buys sexed females, what happens to the males? They do not magically disappear. Every tarantula deserves proper care, regardless of sex. A male is not a failed product, it is simply a different outcome.

Second, raising a tarantula from a sling is one of the most satisfying parts of the hobby. Watching a tiny spiderling grow, molt after molt, into a large, impressive animal never gets old. You learn the species, you learn its rhythms, and you build confidence as a keeper. Buying a large female skips that entire journey.

Third, there is a practical side that people rarely talk about, which is inventory management. When a sling eventually molts out as a mature male, you know that its time is limited. That sounds harsh, but it also means predictability. You know that at some point, a shelf space will free up again. That allows you to plan ahead without constantly expanding your setup or running out of room. In a way, males keep your collection dynamic instead of static.

That said, I have adjusted my buying habits slightly. I no longer buy unsexed slings above a certain size, especially from dealers at expos. If a tarantula has a diagonal leg span of around 5 centimetres (2 inches), it is usually large enough to be sexed. And if there is a realistic chance to sex a tarantula, dealers will almost always do it. Females sell for more money, so there is no incentive not to check.

I still buy slings. I am just more selective about when “unsexed” truly means unsexable.

If you are currently in an unlucky streak, do not let it discourage you. Getting more males than you hoped for is part of the hobby. Unfortunately, statistics do not care about what you would like and what not, and small sample sizes can look unfair for quite a while before they even out.

So yes, buy slings and give them a chance. Accept the outcome. A well cared for male tarantula is still a success story, even if it does not live as long as you wished.

That, too, is part of keeping tarantulas.