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Eggs
The freshly laid egg is pale whitish-blue, translucent, and shiny. Just prior to hatching it becomes bluish-green to turquoise. It is oval-spheroid with parallel sides, blunt rounded ends, and a slightly convex ventral margin. When first deposited, the dimensions are approximately 0.4 x 1.4 mm and 0.5 x 1.7 mm just before hatching. The eggs are laid serially in slits cut in the edge of mature needles, and are covered by a frothy substance (Wilson, 1971;Coppel et al., 1974).
Larvae
The newly hatched larvae are 2.5 mm long, and fully grown larvae are 18 to 28 mm long. The male and female larvae have five and six feeding instars, respectively, with shiny-black head capsules. The fully grown larvae moult to the final non-feeding prepupal or pre-spinning larvae, which spin the cocoon. The body of L1 to L3 instars is uniform yellowish-green, with black thoracic legs. The L4 instar has a mottled colour pattern similar to the mature larvae. There is a double black mid-dorsal line extending the length of the body. On either side of the dorsal stripe is a yellowish stripe broken with transverse brown markings. Laterally the larva has a dark-brown to black field filled with numerous rounded yellow and white spots, many of which protrude from the surface of the body. The ventral side is pale-yellow. The body is sparsely covered with minute spines. The colours of the pre-spinning larvae are very light and pigmentation is strongly reduced.
Cocoon (pupa)
The cocoon is cylindrical with hemispherical ends. It is finely textured, somewhat glossy, and brown. The male cocoons are smaller (7.0 to 8.5 mm x 4 to 4.5 mm) than those of the females (8.5 to 10 mm x 4.5 to 5.5 mm), although there may be an overlap between the sexes. Mertins and Coppel (1972) used seed dockage sieves for the sex-separation of D. similis cocoons.
Adult
Male: 7 to 9 mm, black, abdomen ventral sometimes more or less rufous. Legs yellow, with the trochanters and basal two-thirds of the femora brownish-black. Antenna black with 22 to 24 segments, bipectinate. Penis valve: valviceps triangular, the breadth of the tip less than one-third of the base breadth.
Female: 7.5 to 10 mm, head and thorax mostly black, abdomen yellow and black. Colour pattern variable;some individuals almost dark. Legs yellow, femora partly fuscous. Antenna (including scapus) black, serrate. Lateral bands of the saw (annuli) with teeth (ctenidia) very regular and even.

Related invasive species

  • Diprion similis

Related Farm Practice

  • Feeding
  • Light
Impact


The females of D. similis are poor fliers, therefore most of the expansion of this species in North America has resulted from the movement of infested nursery stock, trees, and foliage (Middleton, 1923;Coppel et al., 1974;Melcher and Townsend, 1999).

Has Cabi datasheet ID
19195
Oss tagged
x

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