Thelasis pygmaea is found in the tropical evergreen forests of South Asia. It is a tiny orchid with even tinier flowers.

Names:
The accepted scientific name of this orchid is Thelasis pygmeae, but previously it was known by various names such as Euproboscis pygmaea, Thelasis triptera, Thelasis elongate, Thelasis capitata etc. It does not have many local names. I could find only one each in English (the tiny thelasis) and Chinese (Ai zhu lan - Blue doll), who call these group of orchids ‘doll orchids’.

Description:
Thelasis pygmaea is a highly variable and adaptable epiphytic orchid. It not only grows on the trees but it is also seen growing on limestone (in Malaysia).

Flowering details:
The light coloured flowers bloom in early summers. Flowers colour varies from white to pale green. Being a miniature orchid the flowers are not prominent.

How to grow this orchid (culture information)
1. Light: It grows better in shady locales, many in company of other larger orchids.
2. Watering: Being a tropical orchid it can take frequent watering which evenly wets the roots. But it would rot if water stagnates around the roots. Humidity should be on the higher level.
3. Air circulation: Keep the air circulating to imitate the natural environment of Thelasis.
4. Growth medium: It can be grown in baskets made of coir. The growth medium should be able to hold some amount of moisture, but should not get waterlogged.
5. Fertilization: Fertilization common to orchids can be given to thelasis also, like NPK (30-10-10).

Pests and diseases in this orchid:
There are no particular bacterial, viral or insect pests of Thelasis pygmaea, but it can get infected from other orchids or plants growing near it. You can give symptomatic treatment in case of infection. If the infestation is acute, insecticide/pesticides used for other plants can also be tried judiciously on orchids.

Lookout for:
• delayed flower or absent flowering (cause can be nutritional deficiency)
• Abnormal colouration of leaves and flowers (indication of disease by bacteria, fungus or virus)
• any distortion in the flower or leaves (can be an indication of disease, pests or nutritional deficiency)
• Early fall of leaves or flowers (can be an indication of disease, pests or nutritional deficiency)
• Chewed off parts (indicating presence of slugs, snails, grasshoppers etc.)

Source
1. Siedenfaden, Gunnar and Jeffrey J. Wood. (1992). The Orchids of Peninsular Malaysia and Singapore.