Hycleus pustulatus is a species of blister beetle found in India, Sri Lanka, China and Java.

While the young are often beneficial to crops by suppressing other plant feeders, the adults can be a problem when present in large numbers.

It feeds on flowers and developing pods of the many agricultural crops such as Hibiscus rosa-sinensis, Pavonia zeylanica, Helicteres isora, Cassia occidentalis, Acacia caesia, Cleome viscosa, Zea mays, Mangifera indica, Murraya koenigii and Tridax procumbens.

Feeding activity is intense during the months of July, August, September and October with flowering seasons of many plants.

[6][7] It is an economically important species due to the ability to biosynthesize potent defensive blistering agent cantharidin.