Acantholyda hieroglyphica

Web-spinning pine-sawfly

Description

The adult sawfly measures around 14-17 mm in length. Females deposit yellow eggs on needles, similar to those laid by Acantholyda posticalis (= nemoralis). Larvae are typically grayish-green, about 20-25 mm in length, and feed on needles of more mature pine seedlings. They reside within a web sac that clings to their frass. On pine trees, annual shoots are formed into brown masses made up of larval frass. While it lives on twigs as early as June, it becomes more noticeable in August when a larger amount of frass is accumulated around its sac. This sawfly is commonly found in young pine plantations and typically lives in small, isolated populations. Damage to trees can occur repeatedly on the same trees, sometimes for several years in a row, which can reduce their vitality and growth. Several other species of sawflies that damage pines in similar ways are also present. The pine false webworm, Acantholyda erythrocephala, is a related species whose larvae construct silken webs, within which they feed in a groups of 3-5.