The larva’s integument was so tough in the second and third instars that standard twenty-seven-gauge injection needles had to be honed before each experiment.Īt the end of its third instar, the larva leaves its log and crawls down into the soil to pupate. Researchers discovered that the best method was to pin down a larva with a patch of quarter-inch mesh, apply heavy pressure to keep the larva from squirming, and inject the disease agent through the mesh. They revived quickly on being handled and intubed. Because they were log-dwellers, with very low oxygen requirements, half an hour of exposure to a carbon dioxide atmosphere was required to knock them out. “Oral intubation” was impossible without a total anesthetic, and the larvae did not anesthetize easily. They could give an entomologist a painful bite, if he was careless. The larvae could chew through hard boards and brass screening. “The grubs react violently to any disturbance and persistently try to bite the object that is in contact with their bodies,” wrote one researcher. In research on diseases that might be used against the beetle on Palau, experimenters had trouble simply in infecting the larvae. The larvae of Oryctes rhinoceros are very strong. Within an hour its head and legs have turned pale pink, and within two hours a pale reddish brown. The larva is white when it first emerges. Then its thorax swells, the old exoskeleton splits, a colorless fluid is released, and the larva struggles free. As it rests in preparation for each molt, it becomes semi-translucent. The dorsum begins to bristle.īetween instars the larva molts. The mandibles develop more complex molar areas. In the third instar, the larva’s head darkens. The left mandible has formed a tooth near the middle of its inner edge. By its second instar the larva’s epicranial suture has become more distinct. At this stage the larva is mostly alimentary canal, for its food is decaying wood, very low in nutrition, and the canal must pass a lot. The larva in its first instar is very small, just a tenth of its eventual length and an even smaller fraction of its eventual weight. Oryctes rhinoceros (Linn), as the beetle is known to the West, or Mengalius, “coconut-eater,” as known in Palau, begins life as a small, clear-white, fine-granulated, hard-shelled egg. of the order Coleoptera, there is a beetle named rhinoceros. In the genus Oryctes, of the tribe Oryctini, of the family Scarabaeidae, of the suborder Lamellicornia. In 1949, on loan from the Department of Agriculture, he was conducting a general entomological survey for the Navy, which then administered the Trust Territory, when the Navy asked him to investigate the beetle on Palau. He jumped at it, and moved with his wife to Guam. A bomberpilot in North Africa during the war, he had left the Air Corps at war’s end and had worked briefly as port entomologist in Hoboken, then Seattle, before the chance came to work in the Pacific. Owen was one of the first officers in the new military government. In winning the islands, the American military had inherited the beetle. “Someone, I can’t remember who, took me all through the limestone islands in a small boat. “From the first day, I knew it was the place I wanted to be.” Owen says. So the horned insect’s god was Mars, and war brought it to the Palau Islands. The damage in Palau was the worst in the world. Many of the trees that survived were injured and their copra production was sharply reduced. Within ten years of introduction, the beetle had killed more than half of Palau’s coconut palms. Logs lay about on every island, making an ideal breeding ground, and the beetle population quickly exploded. In the bombing and shelling, thousands of coconut palms were felled. The Japanese colonial government was too preoccupied with its Pacific war to eradicate the beetle in the first months, while eradication was still a possibility. It probably came as a stowaway on a Japanese vessel from Malaya, Indonesia, or the Philippines. Around 1942 the coconut beetle arrived in Palau, an archipelago in the Caroline Islands of the western Pacific.
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