The tettigoniid subfamily Phyllophorinae, distributed in Southeast Asia and Australia, is poorly known. Our study of the biology of Giant Katydid Siliquofera grandis (Blanchard, 1853) from a laboratory culture has shown that these insects mate more than once, the females lay a total of up to 400 eggs during their life, and these hatch after 2–2.5 months. The life cycle from egg to death takes longer than one year. In the laboratory, the insects fed mainly on leaves of various Rosaceae, Ficus, and lettuce, and on fruits. It is known that the males of hooded katydids lack the tegminal stridulatory apparatus typical for Tettigoniidae, but are capable of producing protest sounds using their coxosternal sound-producing organs for stridulation. Here, protest stridulation of the males and females and the sound-producing organs used to produce it have been analyzed in Phyllophorina kotoshoensis Shiraki, 1930 and S. grandis. In addition, nymphal protest sounds produced by friction of the metafemur against the edge of the pronotum and adult protest signals produced with the wings are described. In S. grandis, vibratory signals have been described and studied for the first time: territorial, protest, drumming and rhythmic low-amplitude vibrations emitted by adults and nymphs and pre- and postcopulatory vibrations of the males and females. The territorial signals not accompanied with visible movements of the body may be produced by contracting the antagonist muscles of the thorax and possibly of the legs. Using their coxosternal sound-producing organs males of S. grandis produced also an audible courtship song lasting for several seconds. Acoustic signals may thus both regulate intrapopulation relations and serve for interspecific communication (protest signals). The acoustic communication in Phyllophorinae is probably especially important during mating behavior.