8 INSECTS AFFECTING THE ORANGE. 



Horticulturists cannot be expected to acquire a technical knowledge 

 of insects attainable only by specialists, but the entomologist can offer 

 in many cases practical suggestions to aid in protecting the beneficial 

 while accomplishing the destruction of the injurious species. In these 

 pages, wherever our present knowledge permits, the ways and means of 

 securing this advantage will be indicated, and it is hoped, by the aid of 

 plain descriptions and figures, to render recognizable to the orange- 

 grower some of the more important beneficial insects with which he is 

 concerned, as well as the destructive kinds with which he must con- 

 tend. 



Presence of certain injurious insects indicated by ants. — 

 Many of the Bark-lice (Coccidse), as well as the common Plant-louse 

 (Aphis) of the Orange produce sweetish secretions, which are greatly 

 relished by ants; indeed, with some species, the honey-dew ejected by 

 these insects appears to furnish the greater part of their food. At all 

 events, whenever any of these nectar-giving insects exist upon an orange 

 tree, ants will be found in attendance upon them, and a stream of ants 

 ascending and descending the trunk of the tree is an infallible indica- 

 tion of their presence. 



The ascending line of ants readily guides the eye to the spot among 

 the twigs and leaves where these enemies lie concealed, and they are 

 especially useful in indicating the whereabouts of incipient colonies, 

 which may thus be destroyed before they have greatly increased, and by 

 their numbers and the extent of their injuries have forced themselves 

 upon our notice. 



Young orange trees are particularly liable to suffer injury from Aphis 

 and the soft-bodied, nectar-producing Coccidse. In the nursery, where 

 the greatest attention should be given to prevent stunting and loss of 

 growth, we may pass rapidly along the rows, and by the presence of 

 ants upon the stocks detect at a glance those plants upon which the 

 pests have obtained a foothold. 



SYSTEMS OF CULTIVATION. 



Influence of shade upon the increase of insect pests. — 

 Most insects love shade. Some, and among the number Scale-insects, 

 the worst pests of the (Jrange, prefer the darkness and dampness pro- 

 duced by dense masses of foliage. Plants, on the other hand, require 

 light and air, for want of which the inner branches pine and lose vital- 

 ity, a condition which also greatly favors the reproduction of Scale-in- 

 sects. 



The good advice of the horticulturist, " Prune back excessive branch 

 growth, give and keep an open head to the tree," may be supplemented 

 and sustained by that of the entomologist, " Let in light and air." Let 

 this not, however, be construed as indorsing the practice of trimming 

 high the trunks, and depriving them of their spreading lower branches. 



