{{Taxobox 
| color = lightblue
| name = 冬蟲夏草
| image = Cordyceps ophioglossoides 02.JPG
| image_width = 250px|
| image_caption = ''Cordyceps ophioglossoides''
| regnum = 真菌界 Fungi
| phylum = 子囊菌門 Ascomycota
| classis = 核菌綱 Pyrenomycetes
| ordo = 肉座菌目 Hypocreales
| familia = 麥角菌科 Clavicipitaceae
| genus = 蟲草屬 ''Cordyceps''
| species = '''中華蟲草 ''C. sinensis'''''
| binomial = ''Cordyceps sinensis''
| binomial_authority = (Berkeley) Saccardo, 1878
}}

'''冬虫夏草'''（''cordyceps sinensis''），又名'''中华虫草'''，是中国传统的名贵中药材，它是由肉座菌目麦角菌科虫草属的冬虫夏草菌寄生于高山草甸土中的蝠蛾幼虫，使幼虫僵化，在适宜条件下，夏季由僵虫头端抽生出长棒状的子座而形成（即冬虫夏草菌的子实体与僵虫菌核（幼虫尸体）构成的复合体）。它主要产于中国青海、西藏、四川、云南、甘肃、贵州等省及自治区的高寒地带和雪山草原。

真正的冬虫夏草均为野生，生长在海拔3000米至5000米的高山草地灌木带上面的雪线附近的草坡上。夏季，虫子卵产于地面，经过一个月左右孵化变成幼虫后钻入潮湿松软的土层。土里的一种霉菌侵袭了幼虫，在幼虫体内生长。经过一个冬天，到第二年春天来临，霉菌菌丝开始生长，到夏天时长出地面，外观象一根小草，这样，幼虫的躯壳与霉菌菌丝共同组成了一个完整的“冬虫夏草”。菌孢把虫体做为养料，生长迅速，虫体一般为四至五厘米，菌孢一天之内即可长至虫体的长度，这时的虫草称为“头草”，质量最好；第二天菌孢长至虫体的两倍左右，称为“二草”，质量次之。

药理学现代研究结果中，青海冬虫夏草含有虫草酸约7%，碳水化合物28.9%，脂肪约8.4%，蛋白质约25%，脂肪中82.2%为不饱和脂肪酸，此外，尚含有维生素B12、麦角脂醇、六碳糖醇、生物碱等。

{{Taxobox
| name = ''Caterpillar fungus''
| image = Cordyceps Sinensis.jpg
| image_width = 250px
| image_caption = ''Cordyceps sinensis''
| regnum = Fungi
| phylum = Ascomycota
| classis = Sordariomycetes
| ordo = Hypocreales
| familia = Clavicipitaceae
| genus = ''Cordyceps''
| species = ''C. sinensis''
| binomial = ''Cordyceps sinensis''
| binomial_authority = 
}}

'''Caterpillar fungus''' ''(Cordyceps sinensis)''  is a  species of parasitic fungus that is found in south-western mountainous China. It attacks and grows on caterpillars, specifically on larvae from the genus ''Thitarodes''. A caterpillar killed by a ''C. sinensis'' fungus growing on it is also called "'''vegetable caterpillar'''" even though no plant matter is involved. It is known in the West primarily from its use in Traditional Chinese medicine, where it is a prized ingredient.

==Names==
In Tibetan it is known as Yartsa Gunbu [Wylie: dbyar rtswa dgun 'bu], source of  Nepali:यार्सागुम्बा, Yarshagumba, Yarchagumba. 
It is also known as ''keera jhar'' or ''keeda ghas'' in India. Its name in Chinese "dong chong xia cao" (冬虫夏草) means "winter worm, summer grass" (meaning "worm in the winter, (turns to) plant in the summer"). The Chinese name is a literal translation of the original Tibetan name, which was first recorded in the 15th Century by the Tibetan doctor Zurkhar Namnyi Dorje (Wylie: Zur mkhar mnyam nyid rdo rje’s [1439-1475]) in his text: Man ngag bye ba ring bsrel (Oral Instructions on a Myriad of Medicines).

In traditional Chinese medicine, its name is often abbreviated as "chong cao", a name that also applies to other ''Cordyceps'' species, such as ''C. militaris''.

It is also known as Aweto in China and Tibet, and as Yarchagumba in Tibet. It is sometimes known as tochukaso/tohchukaso.

==Natural history==
The caterpillar prone to infection by the fungus lives underground in alpine grass and shrublands on the Tibetan Plateau and the Himalayas at an altitude between 3000m and 5000m.   Spending up to five years underground before pupating, the caterpillar is attacked while feeding on roots. The fungus invades the body of the ''Thitarodes'' caterpillars, filling its entire body cavity with mycelium and eventually killing and mummifying it. The caterpillars die near the tops of their burrows. The dark brown to black fruiting body (or mushroom) emerges from the ground in spring or early summer, always growing out of the forehead of the caterpillar. The long, usually columnar fruiting body reaches 5-15 cm above the surface and releases spores.

In Nepal caterpillar fungus is found on the subalpine pastures in Dolpo in Karnali Zone and Darchula in mahakali zone. It is also common in Bhutan and India's Himachal Pradesh. Reports from distribution outside of High Asia are probably erroneous and relate to other species of ''Cordyceps'', e.g. ''Cordyceps militaris''.

It is not certain how the fungus infects the caterpillar; possibly by ingesting a fungal spore or by the fungus mycelium invading the insect through one of its breathing pores.

It is also found in Nandadevi centuary in Uttarakhand Himalayas of India. In the onset of Summer grasslands of Delisera, Dharansi, Malari are populated by the local people, who can be seen crouching on the ground and looking for the "Kira Jari" or the caterpillar root. The locals clean this fungus, dry it and sell it at 100 - 150 rupees (Indian currency) each.

Because of its rarity and value, inter village conflicts over the grasslands has become headache of the local governing bodies.

==Use in Medicine==
===Traditional Chinese medicine===
The first mention of ''Cordyceps sinensis'' in traditional Chinese Medicine was in the 18th Century.<ref></ref>

The entire fungus-caterpillar combination is hand-collected for medicinal use.

The fungus is highly prized by practitioners of fatigue to cancer. It is regarded as having an excellent balance of yin and yang as it is apparently both animal and vegetable (though it is in actuality not vegetable, but fungal). Assays have found that Cordyceps species produce many pharmacologically active substances. They are now cultivated on an industrial scale for their medicinal value.