188 Forty-first Report on the State Museum. 



It is devoutly to be hoped that the " Australian bug," as it is sometimes called, 

 together with the Red Scale {Aspidiotus aurantii) also introduced from Australia, and 

 others of its associates, may not become distributed over the United States, to add to 

 the already almost overwhelming number of our fruit insects. 



There is little danger of the introduction this side of the Rocky mountains of the 

 larger number of the California scale-insects, through the fruit which is being brought 

 eastward, for nearly all of them are fixed to the plant upon which they subsist during 

 their entire life except a brief period following their hatching from the egg. The Icerya, 

 or Fluted Scale, unfortunately possesses habits more favorable to its spread, for it 

 remains free and travels about during the greater part of its existence. In its last 

 stage — according to Professor Riley, to whom we are indebted for the elaborate study 

 of this insect as given in his last annual report,* — and just before the production of 

 its eggs, it shows a disposition to travel in search of some place of concealment, as 

 beneath rough bark. Under this impulse, it might leave the tree and find a convenient 

 hiding-place in some fruit package, and there be conveyed by rail to a distant locality. 

 The common mode of distribution of scale-insects is through the sale of scions and 

 nursery stock. I do not know if these are being brought from California eastward. If 

 such a business has been inaugurated (of which there would seem to be no need), every 

 effort should be made to suppress it, as it would not be possible to institute such a sys- 

 tem of inspection for the detection and destruction of infested stock, as has been 

 adopted by several of the countries of Europe to protect them from the introduction of 

 the terrible Phylloxera pest. 



I have dwelt at some length on these scale-insects, in consideration of their extreme 

 virulence and the harm that will attend their spread. When they have been allowed to 

 gain the footing that they now have in California, it is not possible to exterminate them. 

 The most that can then be accomplished is to reduce their numbers, and to exclude 

 them from localities now free from their presence. I believe that the Icerya has not 

 yet shown itself in the orange groves of Florida. Whenever it shall do so, unless it be 

 met as promptly as we are accustomed to deal with a rabid animal, it is safe to predict 

 that the orange culture of that State is doomed. Arizona is just giving promise of 

 becoming a wonderful fruit region. As yet, it is almost free from frviit pests. Peaches, 

 it is claimed, can there be eaten from the tree from June to December. If so, with 

 proper railroad facilities, we in our Eastern cities could enjoy the delicious fruit during 

 one-half of the year. How desirable it is that such prospects should not be blighted by 

 permitting an influx into Arizona of the scale and other pests which it is possible to 

 exclude, for years, at least. 



Number of Insect Pests. 



I have referred to the large number of our fruit-pests, in species, of perhaps equal 

 importance with the number of individuals, since each one of the species requires sepa- 

 rate study that its particular life-history and habits may be learned, and thereby a 

 knowledge obtained of the best method of dealing with it. If a noxious form, then the 

 most efficient means for its destruction is. to be sought; if beneficial, in the gi'eat ser- 

 vice that it renders in preying upon injurious species, as are entire families, as those of 

 the Ichneumons, Lady-birds, and others — in that case study must be made of how it may 

 best be protected, and its multiplication promoted. 



Of the 325,000 species of insects known to science through name and descri])tion, 

 as existing in the world, 25,000 belong to the United States. Of these 15,000, at least, 

 would be regarded as injurious, fi-om preying upon material serviceable to man. The 

 amount of harm inflicted by many of these is inconsiderable ; and probably not exceed- 

 ing one-half of the number, or from 7,000 to 8,000 may justly be regarded as insect 

 pests. 



The number of fruit insects can not be definitely stated. Four years ago I published a 

 list of 176 species of insects depredating on the apple. Since then I have enlarged the 



» Report of the Commissioner of Agriculture for 1886, pp. 465-492, plates i-v. See, also : Icerya or Fluted Scale 

 Bulletin 15, U. S. Dept. Agricul., Division of Entomology, 1887, pp. 40. 



