Trypodendron betulae Swaine & J. M. 1911

Initial flight in spring (early April) till early May, then June to late summer (Leach et al, 1940).

Transcontinental in Canada; eastern United States (Bright, 1976).

Distinguished by the more coarsely punctured post lateral areas of the pronotum, the dull minutely reticulated surface of pronotum and elytra, with apical margin appearing narrowly rounded from above. Frons of females are convex with surface coarsely, sparsely granulate. In males they are concave with a median tubercle between upper halves of the eyes. The anterior margin of pronotum of females is rounded with two large and two small median teeth. That of males is straight and unarmed (Bright, 1976; Wood, 1982).

Similar to T. retusum in appearance and life cycle (Leach et al, 1940), the difference being on gallery construction which extend deeper into the heartwood in T. betulae. Adults are attracted to Betula spp, particularly B. papyrifera. Before the eggs hatch, the fungus overgrows and overcrowds the cradles. The larvae hatches within a week after the eggs are laid and begin to enlarge the larval cradles until they are slightly bigger than the size of an adult beetle. The fungus is consumed quickly by the growing larvae. The new emerging beetles acquire fungus for inoculation in the next season from fungal cells retained in the intestines of emerging pupae (Leach et al, 1940).

Trypodendron betulae, the birch ambrosia beetle, is a species of typical bark beetle in the family Curculionidae. It is found in North America. It has a symbiotic relationship with Ambrosiella fungi.