| Life Cycle: | The adult European apple sawfly emerges in the spring at about the time apple trees come into bloom. The fly is about 8 mm long. Its head and antenae are yellow, while its eyes are black. The body is brown and shiny and the wings appear to be dusty due to numerous small black hairs. The adults live for approximately two weeks and feed on pollen from the tree's blossoms. It is into the blossoms that the female lays her eggs. The process of inserting her ovipositor through the sepal leaves a distictive brown marking on the sepal which can aid in identifying infested blossoms. Larvae emerge in 1-2 weeks and pass through five instars as they mature. The emerging larvae are less then 2 mm in length. At maturity they are 10 mm and are pale brown in colour. The European apple sawfly larva has seven sets of prolegs. This distinguishes it from other apple eating larvae such as the codling moth, which have only five sets of prolegs. The mature larvae leave the apples, which have usually falled from the tree prematurely, and burrow into the ground where they weave a cocoon and begin pupation. In some cases, the apple sawfly may overwinter for two years. |
| Host: | The European apple sawfly larva feed on apples and crabapples. It has a preference for long-blooming varieties with heavy fruit sets. |
| Bio Region: | Maritime provinces, New England states, Quebec and Eastern Ontario. |
| Damage: | The first instar of the sawfly larva will feed just below the surface of the apple and leave a very distinctive light brown scar originating from the calyx end of the fruit. Later instars will burrow to the centre of the fruit leaving a trail of frass as they tunnel. The damage causes the fruit to drop prematurely to the ground. Either form of damage leaves the fruit unmarketable. |
| Management: | European sawfly infestations are more easy to prevent than control. Remove all dropped fruit. These are often infested and a source of future flies. Traps are a moderately effective component of an overall management strategy. Traps use pheromones as a lure and have a sticky surface to which the fly adheres. In small operations it is possible to bag the fruit so that the sawfly larvae can't get to the fruit. This is both very effective and labour intensive. |
| Controls: | The European apple sawfly is a relative new species in North America and has no nature predators. There are several spinosad formulations that are permitted for use in organic systems that are effective against sawflies; however there are also formulations that use prohibited substances. Producers should check with their certification body prior to use. Kaolin clay, which is approved for many orchard pests, is not approved for the apple sawfly. |
