The raspberry leaf sawfly

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The raspberry leaf sawfly (Priophorus rubivorus Rohwer)4 has been present in California for a number of years. In the spring of 1928, the writers found it abundant and widely distributed in the central district of California. It undoubtedly was present there before 1928. Since bush-berry production in the central district was negligible until about 1916, this species could not have been a pest prior to that time.

In midwinter, when the planting stock of bush berries is transported as bare root plants, the sawfly occurs as prepupal larvae and pupae in cocoons in the soil. The chances that the insect will be brought into the state on planting stock consequently are slight. It seems more likely to be native to the Pacific Coast, probably living on wild bush berries prior to the extensive cultivation of horticultural varieties.

Published records indicate that distribution of the pest is limited to California, Oregon, and Washington. In Oregon, the species was described by (S. A. Rohwer (1922)) from a single female specimen collected on raspberry by E. J. Newcomer at Portland on August 10, 1917. In Washington,5 in 1937, two specimens were collected on Youngberry at Puyallup; and in 1938, damage to bush berries by this species was reported in the state (Hanson, 1938).

Life History

The eggs of the raspberry leaf sawfly are oval, shining, and opaque white. They measure 0.45 millimeter in width and 1.23 millimeters in length. The female is provided with a saw-type ovipositor which she uses to prepare a cavity in the petioles of leaves or in the tender bark of the new shoots. There she lays her eggs singly between the pith and the bark, placing them parallel to the surface of the bark with the long diameter parallel to the axis of the petiole. At San Jose, the incubation period of the egg ranged from 7 to 9 days under outdoor conditions in June.

The newly hatched larvae feed on the undersides of the leaves, cutting small, roughly circular holes between the veinlets, As they become larger the larvae (fig. 1) eat all the leaf tissue between the main veins. This produces large holes, which, by reason of the arrangement of the leaf veins, are frequently triangular (fig. 2). The larvae are solitary feeders and are always found on the lower side of the leaf. They prefer shade, and are always found in the center and low down in the hedgerow, more commonly on the shady side than on the sunny side. The length of the larval period was not determined experimentally, but field evidence indicates that it is from 4 to 6 weeks.