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Species Page - Trypodendron retusum
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scientific name    Trypodendron retusum    

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

Adults are distinguished by their large size, smooth and shining surface of elytra with apical margin appearing subacuminate when viewed from above. Colour is uniformly black when mature but young adults have a pale yellowish brown colouration at the base of the pronotum to the apex of elytra. Length is 3.8 4.6 mm for females and 3.6 4.3 mm for males. Frons are convex with surface reticulated with sparse granules in females. In males they are concave with lateral margins ornamented by abundant hair. In females the anterior margin of pronotum is usually rounded, armed with four teeth, the median pair being larger while in males the margin is feebly recurved and unarmed (without teeth) (Bright, 1976; Wood, 1982).

life history
Over wintered beetles appear and become active in early spring from May until early April. They are attracted to suppressed, dying, withdrawn or dead Aspen cut in the previous season, primarily Populus gradidentata and P. tremuloides. It is the female beetle that initiates tunneling. Boring into the sap wood is fast and completed in a day or two and mating takes place at the tunnel entrance. The male then joins in after mating and assists in removing the accumulated boring dust and frass out of the entrance hole. The female inoculates the tunnels with ambrosia fungus from her mycongia (fungal transmitting gland), (Abrahamson et al, 1967) and boring continues with construction of secondary lateral tunnels. Cradles are then constructed vertically along the lateral tunnels and a single egg is oviposited on each cradle surrounded by the boring material and some fungal cells. Several pairs of beetles use the same gallery with each pair occupying its own branch (Bright, 1976) but one pair for each gallery has also been reported (Brewer et al; 1988). 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. After two larval instars pupation occurs after three to four weeks and the pupal stage lasts for a month after which the adults emerge. Emerging adults are light brown but colour darkens with age. New adults emerge form brood galleries from mid June to early July. In late summer or early fall, the new adults leave the host trees to over winter in forest litter (Leach et al, 1940; Bright, 1976; Brewer et al; 1988).

diet info
Populus spp and Picea spp (Bright, 1976). The larvae gnaw and ingest wood fragments along with ambrosia fungus but only the fungus is completely digested while the wood fragments remain unchanged after egestion (Brewer et al; 1988).

From Alaska to New Brunswick south to California, New Mexico, and West Virginia (Wood, 1982).

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References (5)
Specimen Info
There are 11 specimens of this species in the online database
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Specimen List (11)


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