Seasonal Landscape Problems- Pine Sawflies |
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Sarah Browning, University of Nebraska- Lincoln Extension |
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A serious pest that is making its present felt right now is the Pine Sawfly. Sawfly adults are a non-stinging wasp that lays its eggs inside the needles of pine trees. The larvae hatch out from May to June and resemble a light green caterpillar with a brown or black head. At first the larvae eat only the outer portion of the pine needles but as they mature and grow bigger they start to consume whole needles. The larvae usually feed in groups and will 'rear back' when disturbed. Sawflies are especially damaging on Scotch and Mugo pine, and while usually not a serious problem on mature trees can seriously weaken small trees through defoliation. If only a few larvae are present then simply knocking them off the tree either by hand or with a garden hose can provide good control. The larvae seldom find their way back up onto the tree, and are killed by predators. Larger populations should be treated as soon as possible. Chemical controls, like insecticidal soaps, horticultural oils, carbaryl and permethrin are most effective when the larvae are small. Another insect that is causing damage right now is the Rose Sawfly. Very similar in life cycle to the Pine Sawfly, this insect skeletonizes and chews holes in the leaves of roses. The larvae hatch out in early May and begin to feed on rose leaves by eating away the plant tissue between the leaf veins. As they grow larger, the insects chew larger holes in the leaves and can cause significant defoliation on your rose plants. Rose sawfly larvae are often found in groups, are medium to light green in color with an orange head and are about 1/2 inch long. There is only one generation of this insect per year. Control measures include knocking the insects off the plants with a spray of water or picking them off by hand. If many plants are affected, Sevin can be used for control. However, avoid spraying the rose flowers with Sevin because it is highly toxic to bees. More information: European Pine Sawfly, The Ohio State University Extension European Pine Sawfly, Kansas State University Research & Extension |
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