Please refer also to the following link for details on this group:
Gryllidae = Link 1
Several species of show pronounced entomophagous tendencies, and some seem to thrive on a diet of insect food exclusively. The tree-inhabiting forms frequently attack aphids and scale insects. One 4th instar nymph of an undetermined species is said to have eaten 400-900 individuals of the San Jose scale daily, both the scale itself and the covering being consumed (Fulton 1915). Oecanthus latipennis Riley and O. nivens DeGeer subsist entirely on insect food, mainly aphids of the genus Phylloxera (Clausen 1940).