蔓草虫豆（学名：Cajanus scarabaeoides）为豆科木豆属下的一个种。

Cajanus scarabaeoides is a flowering plant in the genus Cajanus Of the 32 different species within the genus Cajanus, only one, C. cajan (pigeonpea), is cultivated. Cajanus scarabaeoides is the closest wild relative to C. cajan, and is one of the easiest wild species to cross with pigeonpea cultivars. C. scarabaeoides is found naturally in both temperate and tropical zones around the globe. This species has higher levels of drought tolerance, is found to have greater protein content, and has higher levels of resistance to insect pests compared to cultivated types. These genetic traits can be crossed with C. cajan to improve the crop’s productivity. For subsistence farmers, this can reduce economic losses and drastically improve overall crop yield.