Damsel bugs (Nabis kinsbergii) are general predators that will eat aphids, caterpillars and eggs, but seems to prefer very small (just emerged) caterpillars. They are voracious predators which kill their prey by stabbing them with their curved proboscis and sucking out the contents of their victims. They are present in a great range of crops but are especially important in low growing (vegetable) crops.
 

Damsel bug - note the proboscis

Damsel bug attacking a poaoto moth larva in its leaf mine