After 6 or 7 weeks, eggs deposited in twigs by female cicadas hatch and the tiny young (nymphs) drop to the ground, dig into the soil, and remain there for the next 17 years. Fortunately, cicadas are not especially destructive. They do not feed to any extent as adults. There is no stripping of foliage as with gypsy moth caterpillars. Injury to trees is caused by female cicadas as they use their ovipositor to insert their eggs in twigs. This process causes the twigs to die from the egg-laying site to the branch tip (perhaps 1 foot or so). Thus, leaves turn brown and the branch tip generally breaks off or "flags" at the egg-laying site. In most instances, this loss of branch tips amounts to "natural pruning."