This book provides the biology, penetration and emergence behaviour of Hemipteran mermithid, Hexamermis vishwakarma Dhiman that can be used as biological control agents against insect pests (Leptocoris augur) of the Kusam tree. Thus, the entomophilic mermithids offer a promising potential for insect control and these nematodes have been used in different parts of the world as biological insecticides. But, in India, the economic value of mermithids in insect pest control does not appear to have been fully appreciated yet. In India, field trials to control the insect pests utilising these nematodes, are still awaited. Experimental and field trials to control Leptocoris augur (Fabr.) by using H. vishwakarma have yielded significant success and its use as a biocontrol agent is suggested. However, the use of nematodes requires detailed studies on their ecological relationships with the insects prior to biological control operation.