These two sex-related matters aren't obviously closely associated, but there is a nexus between them in South Asia. When a hijra has his private parts excised, he often becomes a prostitute. This seems almost to be a traditional area of employment for hijras; but, considering that HIV and the resulting AIDS have become widespread in India (and, I would guess, elsewhere in that part of the world) I have to think that prostitution has become a risky profession for them. Of course, the intercourse is all anal. I doubt that hijras embark on a life of prostitution because of erotic desires, and, considering that the prostate is said to shrink after orchiectomy, it seems possible that anal orgasms are less intense or nonexistent for hijras.

Beyond that, I recall reading somewhere, though I don't recall where, that prostitutes report that their clients often discuss with them the idea of having the testes or penis and testes amputated. If this is so, I wonder if it is an expression on the client's part of a feeling of guilt or remorse because he is using the services of a prostitute. That is to say, does the person who uses a prostitute's services, perhaps habitually, feel a desire to have his organs removed as a kind of punishment for what he has done, or perhaps to remove the source of a behavior which he considers wrong or embarrassing? Another possiblity might be, that men feel they can talk frankly to prostitutes, who clearly aren't queasy about discussing sex, and that the men discuss deep-seated desires for castration which they don't feel they can talk about with their wives, girlfriends, or anyone else besides the prostitute.

I can't remember reading on this website that anyone wanted to have his testes removed because of his habitually using the services of prostitutes. Is this actually one reason why individuals seek castration, or is the expression of a desire for removal of the testes in that context, simply something that men say at moments when they feel intense regret for doing something which they consider immoral or which is in fact illegal?

A first piece of any answer to your question is to look at who and what the hijra are. While they are usually described as “eunuchs”, most of them would more accurately be described as “Male-to-Female”. There are certainly some Male-to-Eunuch individuals in the community, but most are taking the only route open to them toward becoming as female as possible.

They have their entire external genitals removed. They adopt female names and clothing. They claim to be female in most respects, while recognizing that society does not consider them so.

Until recently, the government has insisted that they are still male.

This “simple” removal of the external genitals has been all that is available for most of the transgendered until very recently.

Even in some rich counties, it is all that most manage to obtain. In Japan, for example, full SRS is available in only a very few hospitals, and with great difficulty. The largest and most active of them recently closed its transgender unit with the retirement of its senior surgeon.

I posted some time ago a brief notice of one Japanese MtF who had her testicles and scrotum removed in one surgery at age 17 and her penis removed at 19 (both, apparently covered under the national health plan, even though age of majority for such decisions in Japan is legally 20). She considered herself to now be female with no further plans for any SRS. I suspect (from a variety of clues, though I haven’t done any research on it yet) that most of the Japanese MtF community have only had a castration and no further surgery.

In India, even those hijra who have managed to obtain a good education before their surgery are generally denied any jobs commensurate with their skills. Prostitution and entertainment have been their major choices. There have recently been efforts to train some of them as hairdressers and beauticians, where they do seem to be gaining some acceptance. I have read of one Indian hijra who is a university graduate in computer science (while still male), but who is now only able to find work as a prostitute after her surgery.

Those who fall outside the traditional gender binary have great difficulties almost everywhere.

A second piece of any answer is to look at how many of the eunuch community were seeking a reduction of an over-active libido. This is a recurring topic in many of the threads here. This doesn’t necessarily include involvement with prostitutes, but it certainly might.