In the spring, the 4mm-long cynipid gall wasp, Diplolepis rosae, lays up to 60 eggs (through parthenogenesis) inside the leaf bud of a rose bush. A week later, the eggs hatch and the larvae begin feeding on the leaf bud. This stimulates the abnormal growth of plant tissue, and a Mossy Rose Gall, covered with a dense mass of sticky branched filaments, is formed. The gall provides the larvae with food and shelter through the summer. In late October, when the Mossy Rose Gall is at its most colorful, the larvae stop eating and pass into the prepupal stage, in which they overwinter inside the gall. In February or March, the prepupae undergo a final molt and become pupae. If the pupae aren’t extracted and eaten by a bird during the winter or parasitized by another insect, adult wasps exit the gall in the spring and begin the cycle all over again.
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Galls, abnormal plants growths caused by many agents including insects, are formed during the growing season on the buds, leaves, roots and branches of plants as a response to chemicals or physical irritation. These galls serve as shelters and a source of food for their inhabitants. Blackberry is host to numerous gall-making insects, including mites, midges and gall wasps, and their temporary homes (galls) are more obvious now that Blackberries have lost their leaves. The Blackberry Seed Gall is caused by a cynipid gall wasp, Diastrophus cuscutaeformis. This wasp gets its species name from the resemblance of the galls it forms to the fruit of Dodder or Cuscuta, a parasitic plant. A cluster of small, globular, seed-like galls within which the gall wasp larvae live are pressed together in a lump surrounding the cane. Each of these 1/10th-inch diameter chambers bears a spine, and together they create a reddish-brown hairy mass.