Pine Needles on Evergreens

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Where did all the needles on my pine tree go?

One of the first insects seen in the spring is the larvae of the European Pine Sawfly. The larvae look like caterpillars, but are actually the larvae of a wasp-like insect. They can be found feeding on the older needles of mugho pines, although will feed on several other species of pine trees. The current year’s growth are rarely touched, but severe infestations can leave a “bottle-brush” appearance to the shrub or tree once all the old needles are eaten. Pine Sawfly have an unusual trait. They are often seen feeding in a large group on a single branch with two or three feeding on the same needle. If you wave your hand over the branch, the larvae will all rear-up simultaneously, as a defense mechanism to scare away predators. Controlling sawfly is fairly easy with any commercially available insect control product that lists sawfly on the insects controlled part of the label. If the population isn’t too large, you can hold a bucket filled with soapy water under the branch and strike the branch to knock them off. If you just knock them on the ground without collecting them, they will just crawl back onto the shrub or tree and continue feeding. Dormant oil applications can also be used to control the very young larvae.