Bugs, Cicadas, Aphids, and Scale-insects 187 



very few years had so naturally increased and spread that the ruthless scale 

 was definitely checked in its destruction, and from that time to this has 

 been able to do only occasionally and in limited localities any injury at all. 



FIG. 254. The fluted scale, Icerya purchasi, attacked by the Australian ladybird-beetle, 

 Vedalia cardinalis. In lower left-hand corner a Vedalia which has just issued from 

 its pupal case. (From life; upper figure slightly enlarged; lower figure much 

 enlarged.) 



Of the second group, the best-known scales are the various species of the 

 genus Lecanium (Fig. 256). Of these, the olive or oleander or black scale, 

 L. olea, as it is variously called, is the most widely distributed and abundant 

 and hence economically important. It is a long-known species, having 

 been described in Europe in 1743, and it was brought to this country in 

 early days. The adult females are blackish, almost hemispherical, rough- 

 skinned creatures, with no external indication of head or other body divi- 

 sions, feet, antennae, etc., all these parts being visible only from the ventral 

 aspect, which normally is closely applied to the leaf or twig. On the back 

 may be distinguished three ridges forming an H. The young are flatter 

 and light brown, but can be recognized by their even more distinct H-mark. 

 This scale is found all over the United States and has a wide range of food- 

 plants, garden-bushes of all kinds, as well as deciduous and citrus fruits 

 being attacked. In California it is one of the worst insect-pests of the olive- 

 tree and also one of the worst of the orange enemies. It has certain natural 

 enemies in the persons of various ladybird-beetle species, and a few special 

 ladybird-beetles have been imported from Australia and elsewhere in the 

 hope of repeating the signal Vedalia success. Only a fair measure of suc- 

 cess has been achieved. An indirect but serious injury caused to plants 

 by the black scale is due to the germination in the honey-dew secreted by 

 it of the spores of a fungus, Capnodium sp., which spreads its felted mycelia 



