Comparative investigations of the distal part of the vesica spermalis (‘glans’) of the anisopteran male secondary copulatory apparatus reveal three different ‘solutions’ of combining the emptying-mechanism of the sperm-reservoir with a ‘washing out’ of sperm of the male predecessor. The responsible apparatus of the glans—actually driven by pressure-changes inside the erectile organ, which is a…
A terminology is presented for structures and events in larval development of Odonata with the aim of bringing terms into conformity with those used for other insect orders in the light of accepted views of homology. The terms ‘exuvia’, ‘larva’, ‘prolarva’ and ‘stadium’ receive special mention. Records of the number of stadia required to complete…
Male aeshnid dragonflies at a small pond (circumference ca 90 m) in Cambridgeshire U.K. generally pursued males of other aeshnid species as well as their own. As a result of these encounters the pursued insect frequently left the pond, particularly when it belonged to a smaller species. Libellulids, which differed greatly from the aeshnids in…
In the dragonfly Anax nigrofasciatus nigrofasciatus (Aeshnidae, Anisoptera), the X-tissue is the tissue which occupies the posterior corner of the larval eye and which forms the large facet region in the dorsal part of the adult compound eye after emergence. In the early period of the last larval instar, an ommatidial retinula of the X-tissue…