TWENTY-NINTH FRUIT-GROWERS CONVENTION. 



155 



longidus of our citrus trees, and the apricot and prune scale of our 

 deciduous orchards. Of the third division we have the red scale, the 

 yellow scale, San Jose scale, the small round white scale (often referred 

 to as the lemon-peel scale), the greedy scale, the purple scale, and the 

 narrow, slim rose scale. All these species are serious checks to the 

 vigor of the plants which they infest, and all would call for great 

 expense of time and money to stay their havoc, except that in several 

 cases their natural enemies become our effective abettors. 



I wish to impress upon you two facts in the life history of scale 

 insects that are of practical import in our battle with these pests. The 

 ovoviviparous species, in which group the young are born alive, are 

 hatching all the season through in our genial California climate, and 

 thus we find scale of all ages at any time. Even the oviparous species, 

 like the black scale and the purple scale, are wont, in our warmer 

 seasons, to anticipate the usual hatching time, and thus want of uni- 

 formity is not rare in the hatching of these egg-laying coccids. The 

 fact that the older scale insects are very difficult to kill by any known 

 method makes this a matter of great moment in our practical work in 

 this contest. Thus with many scale insects always, and vnth almost 

 any species at times, two applications of an insecticide within a few 

 weeks are absolutely requisite to complete success. This fact must be 

 faced in planning our orchard economics. 



Again, the armored scale pests are protected by their coat of mail 

 and so are less easy to successfully combat than are the others. This 

 matter should not be lost sight of as we consider the scale pests and 

 plan for their overthrow. 



Natural Enemies. — Xo one who has not studied scale insects in the 

 field can have any adequate conception of the value and importance of 

 our insect friends. Many which would be our most formidable foes are 

 wholly kept under by these Lilliputian friends. The greedy scale, the 

 lemon-peel scale, the yellow scale, the apricot scale, the soft brown scale, 

 the prune scale, and most important, the cottony cushion scale, have 

 all lost their terror because of their insect enemies. Surely, we little 

 appreciate our debt of gratitude to this great host of efficient insect 

 friends. 



Insects, like fish, form the rich, coveted menu of a great army of life 

 forms. So insects, like fish, are enormously prolific. They must repro- 

 duce sufficiently to feed millions, and yet provide for the continuance 

 of their own species. This very fact of redundant egg-laying would be 

 quick proof to any naturalist that natural enemies in the native habi- 

 tat of any such animal were legion. Our scale pests are striking 

 examples. My students have counted over four thousand eggs under 

 one prune scale and over three thousand under one black scale. The 

 ovoviviparous species are a close second in this enormous fecundity. 



