Monochamus marmorator Classification Family Cerambycidae > Subfamily Lamiinae > Tribe Monochamini > Genus Monochamus Diagnostic Features of Larvae Larva. Very difficult to separate from Monochamus scutellatus. In the earlier stages the asperities are much coarser on the pronotum and ampullae. Mature larvae are considerably more hairy, the tubercles on the ampullae are broader and less projecting and the abdominal spiracles are nearly orbicular with a very heavy peritreme usually more darkly colored. The hairiness can be expressed by comparison of the group of hairs at the extremity of the lateral suture of pronotum. In Monochamus scutellatus this group varies from 6 to 10, while in Monochamus marmorator from 12 to 20. Adapted from Craighead, 1923). Biology and Economic Importance This insect is of much economic importance in balsam following spruce budworm outbreaks in eastern Canada and northeastern United States. It attacks the defoliated and weakened trees, causing their death. The adults are active at night, ovipositing under the balsam pustules on the trunk. The large egg punctures and copious flow of balsam from the wounds are very characteristic features of their attack The larval mines are more transverse than other species, thus more quickly girdling the tree. Adapted from Craighead, 1923). Selected References to Larvae Specimens Craighead, 1923