Aren't darba found in the beds or on banks of Karamana or Neyyar? It is that like us they don't take the hardship of locating them? Snakes were there even in earlier times too.
Most vadhyars just cut the length of thread for making "yagnopaveetham" rather than drawing threads with charka, thakli or just by rolling the hand.
Dear Shri Swami,
'yajnopaveetam' in fact refers to an 'upper garment' (upa +veeta) to be used compulsorily during any vedic sacrificial ritual by the "yajamaanan". neevee was the lower garment of those vedic days. References to a custom of wearing an upper cloth or a thread, at all times
is not found in the earliest scriptures. In the sutra period, by which time perhaps the thread had come into vogue, there is specific mention of "upaveetam" in the times of Manu. I give below the relevant portion of Manu Dharma Sastra:
41. Let students, according to the order (of their castes), wear (as upper dresses) the skins of black antelopes, spotted deer, and he-goats, and (lower garments) made of hemp, flax or wool.
42. The girdle of a Brahmana shall consist of a of a triple cord of Munga grass, smooth and soft; (that) of a Kshatriya, of a bowstring, made of Murva fibres; (that) of a Vaisya, of hempen threads.
43. If Munga grass (and so forth) be not procurable, (the girdles) may be made of Kusa, Asmantaka, and Balbaga (fibres), with a single threefold knot, or with three or five (knots according to the custom of the family).
44. The sacrificial string of a Brahmana shall be made of cotton, (shall be) twisted to the right, (and consist) of three threads, that of a Kshatriya of hempen threads, (and) that of a Vaisya of woollen threads.
45. A Brahmana shall (carry), according to the sacred law, a staff of Bilva or Palasa; a Kshatriya, of Vata or Khadira; (and) a Vaisya, of Pilu or Udumbara.
46. The staff of a Brahmana shall be made of such length as to reach the end of his hair; that of a Kshatriya, to reach his forehead;
(and) that of a Vaisya, to reach (the tip of his) nose.
47. Let all the staves be straight, without a blemish, handsome to look at, not likely to terrify men, with their bark perfect, unhurt by fire.
48. Having taken a staff according to his choice, having worshipped the sun and walked round the fire, turning his right hand towards it, (the student) should beg alms according to the prescribed rule.
49. An initiated Brahmana should beg, beginning (his request with the word) lady (bhavati); a Kshatriya, placing (the word) lady in the middle, but a Vaisya, placing it at the end (of the formula).
50. Let him first beg food of his mother, or of his sister, or of his own maternal aunt, or of (some other) female who will not disgrace him (by a refusal).
51. Having collected as much food as is required (from several persons), and having announced it without guile to his teacher, let him eat, turning his face towards the east, and having purified himself by sipping water.
52. (His meal will procure) long life, if he eats facing the east; fame, if he turns to the south; prosperity, if he turns to the west; truthfulness, if he faces the east.
It will be seen that reference is made to a girdle (very much like the Kusti of the Parsis at the time of their initiation into the Parsi religious fold - see here
for details and how closely it resembles the upanayana). The general instruction regarding the yajnopaveeta (I can't say when the ancient 'girdle' changed to 'cross belt') is that if it falls below the navel it becomes impure. You will find even today that Namboodiris wear an angavastram neatly rolled into a rope-like form and wear it on their (left) shoulder with a "brahma mudicchu" to keep it secured to the body, when doing any rites at home or in a temple.
Hence, it is salutary that the length of the poonal is suitably curtailed.
Do you know that most vadhyars get the thread wholesale from Madurai and upaveetham is made as a household manufacture by women sitting at home? These women are supplied with the thread and paid at piece-rates. In TVPM there is a small factory manufacturing cycle tyres and strong, reinforced cotton-rayon mix yarn is used there. Some vadhyars here get the thread from that factory - on payment, of course - and use it because the poonals will not normally break for one year.
Coming to "darbhai" I am surprised by your statement "Snakes were there even in earlier times too."
I wonder in what an insulated world you are, that you seem to be unaware of the profound changes our kerala has undergone socially in the last few decades.
In earlier times there were people who had their avocations decreed by the caste system and they had to do certain jobs (only) or beg/starve. Today the Kerala people can take up any secular employment. Many have done that and gone to the gulf countries, and their gennext have done the same; even those who did not go out, do not have to take up this risky job for earning their livelihood. And, they just no longer believe that the few thousands of "cross-belted swamis" doing some abracadabra is of any relevance to or has any impact on their well-being.
Darbhai growing areas have vanished due to large scale reclamation of hill sides for housing, farms and what not. Very few people need to do this and so vadhyars have to cajole the few fellows and keep them in good humour if some supply is to come. So the supply is very limited, cost high.
The shortage of persons is not only for this; it is felt in getting supplies of ayurvedic herbs, skilled workers like masons, plumbers, electricians, carpenters, tile-layers, even unskilled labour for concreting, maids for household jobs, etc. Surely Kerala is moving towards the egalitarian west.