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Compared with simple eyes, compound eyes possess very large view angles and better acuity than the insect's dorsal ocelli, but some stemmatal (= larval eyes), for example, those of sawfly larvae (Tenthredinidae) with an acuity of 4 degrees and very high polarization sensitivity, match the performance of compound eyes.
At the end of each tracheal branch, a special cell provides a thin, moist interface for the exchange of gases between atmospheric air and a living cell. Oxygen in the tracheal tube first dissolves in the liquid of the tracheole and then diffuses across the cell membrane into the cytoplasm of an adjacent cell. At the same time, carbon dioxide ...
Some cockroaches have just six ganglia in the abdomen, whereas the wasp Vespa crabro has only two in the thorax and three in the abdomen. And some, like the house fly Musca domestica, have all the body ganglia fused into a single large thoracic ganglion. The ganglia of the central nervous system act as the coordinating centres with their own ...
Drawing of dorsal view of an adult female P. pensylvanica (Plate VI, figure 3), as well as views of body parts of the species, and drawings of other species. From 1917 Memoirs of the American Entomological Society , with keys to P. pensylvanica figures on pages 278–280.
The desert cockroach can gain weight by absorption of water vapor from unsaturated atmospheres above 82.5% relative humidity.Blocking the anus or the dorsal surface with wax does not prevent water vapor uptake, but interference with movements of the mouthparts or blocking the mouth with wax prevents such uptake.
The American cockroach (Periplaneta americana) is the largest species of common cockroach, and often considered a pest. In certain regions of the U.S. it is colloquially known as the waterbug, [1] though it is not a true waterbug since it is not aquatic. It is also known as the ship cockroach, kakerlac, and Bombay canary. [2]
Dorsal ocelli ubiquitously have massive convergence ratios from first-order (photoreceptor) to second-order neurons. [ clarification needed ] These two factors have led to the conclusion that, with some exceptions in predatory insects, the ocelli are incapable of perceiving proper images and are thus solely suitable for light-metering functions.
A cockroach's cells divide only once each molting cycle (which is weekly, for the juvenile German cockroach [68]). Since not all cockroaches would be molting at the same time, many would be unaffected by an acute burst of radiation, although lingering and more [ clarification needed ] acute radiation would still be harmful.