10 REPORT ON PARASITES AND PREDACEOUS INSECTS. 



are always present in large numbers with the black scales. These are: 

 Orcus australasia, Rhizobius ventralis, R. hirtellus, Cryptolsemus Mont- 

 rouzieri, and the larva of the Thalpochares moth, which alone is able to 

 free whole trees in a very short time. It is only upon bushes or young 

 trees generally covered with large numbers of ants, which prevent the 

 predaceous insects from coming near, that the black scales become 

 numerous. Upon old trees these coccids are but rarely found in num- 

 bers, and if so, only upon an occasional branch, which is speedily 

 cleaned again by the numerous predaceous insects preying upon them. 



The red scale (Aspidiotus aurantii) is, perhaps, aside from Mytilaspis 

 Gloverii and Chionaspis citri, the most numerous coccid upon citrus 

 trees in Australia, and in fact is at present the most injurious to citrus 

 trees in that country; but its progress is checked by its natural enemies. 

 Australia is in possession of more than enough natural enemies to keep 

 this coccid in check with ease, although nearly all these are preyed upon 

 by parasites. To spray or fumigate to kill the red scale would also mean 

 the destruction of the numerous beneficial insects, and those that were 

 not killed outright would mostly leave the orchard in search of other 

 food, and the consequence would be that in a few months the trees 

 would again become infested, with but few enemies present, and the 

 scales would do great damage unless " the spray is again applied." 



As it is, at the present time in Australia, orange and lemon trees are 

 often planted in almost any locality, without regard to the situation, 

 condition of soil, drainage, climate, and other conditions. The conse- 

 quence is that some of these orchards become diseased, presumably 

 from the effects of the red scale, and, as is the case in the Gorden dis- 

 trict, near Sydney, one tree after another will succumb. An examina- 

 tion showed that these trees had been planted in heavy, clayey soil, 

 without any drainage, and were invariably destro} T ed by the so-called 

 " foot-rot." The fact is, that if an orange or lemon orchard, as the case 

 may be, is left for years without any attention whatever, the weeds 

 allowed to grow, and planted in an unsuitable location or soil, before 

 very long the leaves become yellow and drop off slowly, and in time the 

 remaining green leaves become covered with red scales, since, as is 

 always the case, the predaceous insects preying upon this scale will not be 

 found on such trees, as they prefer those with dense foliage and shade. 

 Such trees may thus linger for months, or even years, before dying, and 

 may even again recover if proper attention is given them. In one of 

 such orchards, of several acres in extent, but a few living twigs covered 

 with red scale were found, yet not a single one of the many predaceous 

 insects preying upon them could be noticed. In another instance, an 

 orchard of some eight or ten acres and about thirty-five } r ears old, 

 the proprietor of which always supplied sufficient manure and kept 

 the ground cultivated, during the whole time of its existence had been 

 infested with red as well as other scales, and yet but a very few trees 

 along the border of one side could be found that showed any traces of 

 such. The whole orchard during the thirty-five years had never been 

 pruned or sprayed, nor even had the trunks ever been washed. Numer- 

 ous dead limbs were present, the stems and limbs partly covered with 

 lichens, and yet I did not meet with a finer lot of trees in Australia — 

 such glossy, deep-green foliage, abundance of fruit, and so free from 

 scale. 



