SOME SCALE INSECTS. 91 



relied upon to be uniform in composition and strength, and, if 

 possible, to have some authoritative supervision to insure such 

 results. 



We have, then, two mixtures upon which we can rely. First, 

 the standard kerosene emulsion, diluted with ten parts of water, 

 for application to the trees while in full foliage in summer and 

 autumn. Second, whale-oil soap at one and three-fourths pounds 

 to the gallon of water, applied in the late fall and early spring 

 to the dormant scales. 



Natural Exemies of Scale Insects. — The extraordinary 

 results which followed the introduction of the Australian lad}^- 

 bird (or ladybug as it is more frequently called) into the orange 

 groves of California at a time when their complete destruction 

 was threatened by the white or cottony cushion scale, have 

 attracted an enormous amount of attention to this method of 

 fighting scale insects. As has been repeatedly pointed out in the 

 publications of the Department of Agriculture, this instance 

 was exceptional, and, in fact, practically unique. We had an 

 imported insect to deal with ; we had ascertained its original 

 home ; we knew that in its original home it was not abundant or 

 destructive, and that therefore it was being kept in check by some 

 specific enemy, since other species of scale insects abounded 

 there and were injurious to vegetation. With no other imported 

 scale insect at the ]3resent day do we have these grounds to work 

 from. Nevertheless, this fact is ignored, and persons whose 

 orchards are suffering and who are disinclined to go to the 

 trouble and expense of spraying, are continually agitating the 

 question of parasites and natural enemies. The first Australian 

 ladybird, the Vedalia, as it is called, is being constantly asked for 

 for all sorts of scale insects, and its careless distribution has, in 

 one instance at least, resulted not in a benefit to the section into 

 which it was introduced, but in a great detriment, since, with 

 the predatory insect itself was sent a supply of the fluted scale 

 as food, and when the specimens were liberated the Vedalias 

 died and the scale insect established itself in new territory. A 

 great deal has been said about the merits of the later importa- 

 tions of predaceous insects from Australia to California. Mr. 

 Koebele, the original discoverer of the Vedalia, during an 

 extended trip to New Zealand and Australia, sent to California a 

 number of species of Coccinellids, which were found by him to 



