THE PHYLA ARTHROPODA AND ONYCHOPHORA 



Fig. 15.20. A locust, Trimerotropis 

 coemleipes. A, mature female deposit- 

 ing a packet of eggs in the ground, 

 having dug a hole with her ovipositors. 

 B, a young nymph. Note the dififer- 

 ences in proportions, and in develop- 

 ment of the wings, between nymph 

 and adult. (.-1, from E. S. Ross, Insects 

 Close Up, copyright 1953 by Uni- 

 versity of California Press, reprinted 

 by permission; 5, photograph by 

 E. S. Ross.) 



male to female at copulation. In the female there are two ovaries, lying in a 

 position corresponding to that of the testes in the male. Each ovary is com- 

 posed of large numbers of tubular ovarioles in which the ova are formed. The 

 ovarioles have a common anterior origin in the ovarial ligament, and all the 

 ovarioles of each side unite posteriorly to form an oviduct. Passing ventrally 

 like the ductus deferentes of the male, the two oviducts join beneath the in- 

 testine into a median tube, the vagina, which opens externally between the 

 valves of the ovipositor. A small, tubular appendage of the vagina, the seminal 

 receptacle, receives and stores spermatozoa transferred by the male at copula- 

 tion. At the time of oviposition, eggs pass singly down the oviducts and 

 through the vagina; as they move past the opening of the seminal receptacle, 

 they are penetrated by spermatozoa from the stored supply and so leave the 

 vagina as zygotes. The female deposits these zygotes, called "eggs," in 

 masses of several dozen, placing them in the soil in holes dug beneath the sur- 

 face by thrusting movements of the abdomen and ovipositor (Fig. 15.20). In 



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