Garden Pests: The Rose Saw Fly

Roses are off course quintessentially British. The typical British garden is incomplete without a rose, whether it's scrambling over a trellis, featured in a formal rose bed, or simply poking its blooms through a modest gap in a cottage garden delight. They repeat bloom, they smell delicious, and though relatively inexpensive they have become the world's most tender romantic gift. However, far be it for Mother Nature to let them get away scot free. The rose sawfly is on the attack and there's hidden horror behind a rather innocuous looking pest.

Easily spotted due to their vivid orange abdomen, the rose saw fly comes in a variety of species, albeit looking very similar. Selecting new, soft shoots, the female can be seen laying eggs into the small wound that they create. After the female leaves, this wound often becomes woody, split and bulbous typically causing problems for any shoots trying to grow above the inflicted mark.

However, this is the least of damage that the rose sawfly causes. Upon hatching, the army of freshly hatched larva march over the plant, quickly stripping leaves to all but a sorry strand of green. Moving in family groups and looking similar to caterpillars, the larvas grow rapidly as they strip the plant before moving into the soil to pupate. With up to 3 generations occurring between May and October, real and permanent damage can occur to beloved roses.

By far the easiest solution is to nip the problem in the bud by preventing the larva from hatching in the first place. Adult females, easily spotted by their yellow/orange colour, will attach themselves to roses in an attempt to lay eggs. By looking closely at growing shoots and tips, individual females can easily be squashed, as once egg laying has started the flies find it difficult to fly away. Keep an eye on the area of the rose where she was seen. If the stem starts to darken, split or turn brown cut it off several inches below the damage to prevent hatching larva spreading through the plant.

If larvas are already present on the plant, there are a number of options. If not sentimental over plants, let nature follow its course and you'll soon notice birds taking the young away to feed to their fledglings. This does mean a certain amount of damage to the plant first though, so alternatively remove the larva either by picking off individually, or pruning off the infested stem and disposing.

It is often difficult to completely rid a plant of all sawfly larvas, and by far the easiest and quickest way is to squash all adult flies on sight. Whilst this may not seem pleasant, it will save you much time and energy later on, and your roses will be eternally grateful.