Their large size is a typical and obvious characteristic in the family, with lengths up to . The following distinct features are diagnostic characters, based on research by Ronquist and Liu and Nordlander.
Body The genae are swollen and pronounced. The female
antenna consists of 11 segments, while the male antenna consists of 13 segments. A large portion of the
pronotum is well developed, called the dorsal pronotal area, with
scutellar processes. The marginal cell of the forewing is elongated and thin. The
gaster is long and pronouncedly compressed laterally. The seventh
tergum is large in females. An apical tubular process is present on the second
tarsomere of the hind leg. The
metafemur is short, no longer than the
metacoxa.
Reproduction and parasitism The female lays the egg by
oviposition through the oviposition shafts created by
Siricidae, and the egg is deposited inside a
siricid larva. In the species
Ibalia drewseni Borries,
Ibalia leucospoides (Hochenwarth) and
Ibalia japonica Matsumura, host detection by
symbiotic fungus in the siricid has been observed. The larva lives it in its first instars as an endoparasite, and later exits the host and lives on the remaining host tissues. The primary
instar is polypodeiform with paired appendages on
segments 1–12, and in the second to fourth
instars, the appendages are lost. Until the terminal
instar, the remaining
cauda is gradually decreased. The two subgenera of
Ibalia differ in host choice, the subgenus
Ibalia parasitizes coniferous-living
Siricinae larvae and the subgenus
Tremibalia parasitizes hardwood-living
Tremicinae larvae. Few details are known about the genera
Heteribalia and
Eileenella, but both also parasitize wood-boring Siricidae.
, host of Ibalia leucospoides'' ==Pest control==