Larvae are about the same green color as the leaves and are difficult to see because they rest inside the edges of the feeding area. Sawfly larvae differ from moth larvae in that they have more than five pair of prolegs and the prolegs have no crochets. Maturing larvae are about 0.5 inch long. These pests are foliage feeders and do not attack fruit. Most eggs hatch by petal fall and larvae immediately begin feeding on leaf tissue in a circular pattern within or along leaf edges, leaving round or oval holes.
Several larvae can consume an entire leaf, leaving only the midrib.
Randomly sample one leaf on each of 100 trees in a block. If there are less than six infested leaves per block, no action is necessary. If 6 to 24 leaves are found infested, monitor the infestation weekly for further increases in numbers and damage. When 25 or more of the sampled leaves are infested, advance the first codling moth cover spray. If no codling moth have been trapped at this time, however, California pear sawfly can be adequately controlled with the low rate of azinphosmethyl, or one-half the rate listed below for diazinon.