European Pine Sawfly
European Pine Sawfly
Sawflies look a bit like big flies. Don't be fooled; they're more closely related to bees, wasps and ants. Many sawfly species are host plant-specific. In other words, a female sawfly will lay her eggs on the same species or genus each year, which in this case is Pinus. This way, the larvae can begin feeding as soon as they hatch from the egg! These insects give rise to larvae that look remarkably like caterpillars. In large numbers, they can make short work of pine, especially when trees have not yet established.
Caterpillar larvae defoliate trees in large numbers.
Mature adults can provide pollinating services in the garden.
Adults: Adult sawfly looks like black/brown flies. The wings appear a tainted black, and the legs and abdomen have a brownish-red gradient. Adults, which are most prevalent in late summer to autumn, however, are less likely to be seen by the gardener. Larvae: They look very much like caterpillars. They will always be closely associated with plants within the Pinus genus. They are a dull greenish-grey, with either pale or dark vertical stripes along the body. They have shiny blackheads and pale green stumpy legs. They're often seen feeding in large aggregations. Eggs: They're laid on needles but are too discrete to be seen with the naked eye.
Can defoliate small trees or whole sections of larger plants. May stunt growth in large numbers.
Europe and North America
Treatments may be ineffective if the infested plant is too big. It's thought larger trees can tolerate infestations. If trees are small, you can pick off caterpillars and feed them to the birds! Attract natural garden predators into the garden by providing spots of cover. Wild patches and strips of native wildflower/ grass can provide cover for predatory insects. Climbing plants such as ivy is excellent habitat for small songbirds. Likewise, bird tables and ponds are an excellent resource for attracting wildlife.
If infestations are substantial, and trees reasonably sized, there are chemical alternatives. There are chemical alternatives available for home use, and these vary in the degree of persistence and strength. These include organic sprays (containing natural pyrethrums); winter washes (these contain plant oils and work best on vines); there are more persistent chemicals containing synthetic pyrethroids. Plants intended for consumption should not be sprayed unless stated on the bottle label. Never apply to flowering plants.