326 



BENEFICIAL INSECTS. 



Among tlie insects which are of great service in de 

 stroying- other insects that are injurious to crops, the lady- 

 birds (Coccinellidce) are probably the most prominent. There 

 are many species of these, which prey on various kinds of 

 crop pests in every country of the world. Perhaps the most 

 noteworthy is the Vedalia cardinalisy introduced from 

 Australia, which has done very great good in the orchards of 

 America by clearing off the scale insect, leery a Purehasiy so 

 destructive to almost all kinds of trees in that country. In the 

 opinion of many entomologists in the United States, this scale 

 insect would have caused great injury to American fruit crops, 

 as it was spreading rapidly, if the Vedalia had not been intro- 

 duced by the late Professor Riley, and carefully protected by 

 those interested in fruit culture. 



There are several species of Coccinellidce in Great Britain 

 which are of inestimable benefit to farmers, fruit growers, and 

 gardeners, as they live principally upon aphides and minute 

 fungi, such as the UstilaginecB and PeroiiosporecB. Professor 

 Forbes, of Illinois, in a treatise upon the " Food Relations 

 of the Carahidce and CoccinellidcB" gives the result of a 

 series of dissections of species of the latter family of 

 beetles, with a view to ascertain the nature of their food. 



The result of these examinations was that the food of the 

 Coccinellidce was on the whole simple and uniform, consisting 

 almost wholly of plant lice, spores of fungi [Cladospo7'ium^ 

 Uredo, Septoria^ Helminthosporium and Pcronospora) and 

 pollen grains. The food varied but little in the different 

 genera of this family. In all cases the perfect or adult insects 

 were examined ; no larvae were dissected, but it would 

 probably have been found that they had eaten a far larger pro- 

 portion of animal than of vegetable food. The ladybirds, when 

 in the beetle stage, are not nearly so intent upon feeding as , 

 their larvae, but seem more bent upon finding convenient 

 spots for egg-laying and basking in the sun. Their mouth 

 organs are not so well adapted for eating plant lice as the 



