RIIYXCHOTA. 



569 



and develop, protected by the drying -up body of the mother. They are generally 

 fertilized (Coco us), but sometimes develop parthenogenetically (Leoanium, 

 Aspld'wtufT). Unlike the female (and forming a single exception to what 

 otherwise obtains in the order), the males undergo a complete metamorphosis ; 

 the apterous larvaa surround themselves with a cocoon, and are transformed into 

 quiescent pupae. Many Coccidee cause great damage in conservatories. Others 

 are useful in industry, in that they produce a colouring matter (cochineal), 

 while others are useful in causing, by their puncture, an outflow of vegetable 

 juices which when dried, are used by man (lac, manna). Axpidiotus ncrli. 

 Bouche, found on the Oleander, Lecanium hesperidum L., L. perxica: Bouche\ 

 Kcrmcs ilicis L., on Qucrcus coccifera, also K, 1 (Coccus) lacca Kerr., on Ficus 

 religiosa in the East Indies. Coccus cacti L., (tig. 472) lives on Opuntia 

 coccinellifera, Mexico, gives cochineal. C. adonidum L., C. (?) mannijHirus 

 Ehbg.. on Tamarix (manna). 



Fam. Aphidse,* plant-lice. As a rule, there are four transparent wings, with 

 a scanty venation. The wings may, however, be absent in the female, and 

 rarely in the male. The Aphides live on vegetable juices, and are found on 

 roots, leaves and buds of quite definite plants. 

 They frequently live in the spaces of gall-like 

 swellings or deformities of leaves, which are 

 produced by the punctures of the plant-lice. 

 Many of them possess, on the dorsal surface 

 of the antepenultimate segment, two "honey 

 tubes," from which is secreted a sweet fluid 

 the honeydew which is eagerly sought for 

 by ants. In addition to the usually apterous 

 females, which, as a rule, only appear in 

 autumn with the winged males and lay 

 fertilized eggs after copulation, there are 

 also viviparous, usually winged generations, 

 which appear principally in the spring and 

 in Slimmer, and which produce their living 

 brood without the assistance of males. Bon- 

 net observed nine generations of viviparous 

 aphides succeed one another. They are distin- 

 guished from the true oviparous females, not only by their form and colour, and. 

 in many cases, by the possession of wings, but also by essential peculiarities in 

 the generative apparatus and the eggs (pseudora, germs). The receptaculum 

 seminis is absent, and the eggs undergo their embryonic development in the very 

 long egg-tubes. Viviparous and oviparous aphides usually succeed one another 

 in regular alternation, since the females lay fertilized eggs in the autumn, 

 which survive the winter and in the spring give birth to viviparous aphides, 

 the descendants of which arc also viviparous, and produce viviparous forms 

 through a number of generations. It is only in the autumn that the males and 

 the oviparous females are born which copulate. Viviparous individuals of many 

 forms seem to pass the winter in ant-hills. Sexual forms (at time of birth 

 already mature, wingless and without proboscis) are sometimes found in the 

 spring ; they are in all probability produced by such viviparous forms which 

 have persisted through the winter. This has been shown to be the case for 



a 



FIG. 472. Coecui cacti, a, Female. 

 b, Male (after Burmeister). 



* Derbcs, "Notes sur les Aphides du pistachier turebinthe." Ann. dcs Sc. 

 Nat. 1872. 



