Answer: Are they caterpillars or are they tadpole looking critters? The tadpole looking critters are pear slugs. These pests eat the leaves of pears, cherries, plums, apples, quinces and hawthorns. The adult is a glossy black sawfly; it lays eggs in the leaf, which become slug-like larvae. After feeding on leaves, they drop to the ground and dig into the soil, where they pupate. Adults emerge and fly to the leaves to lay more eggs. There are 2 generations a year; the first larvae appear on trees in early summer. These become adults in December and January. The 2nd generation is usually more of a pest than the 1st, more numerous and widespread. Some of the larvae over-winter underground to emerge the following spring to start the cycle again. You can hose them off your tree to stop them from feeding, or use insecticidal soap applications. If what you see are truly caterpillars, you can control them with Bt, sold as Dipel or Thuricide in garden centers.
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