448 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



and must be an important factor in reducing the numbers for the suc- 

 ceeding year. 



Since the Scutellista is generally distributed throughout the citrus 

 belt of Southern California, little can be gained by turning loose a 

 half dozen specimens in a grove of 10, 20 or 40 acres where there are 

 already many hundreds or thousands, except for the moral effect on 

 the grower. Sometimes the scale may largely disappear the follow- 

 ing year, and sometimes the Scutellista may be a great help in this 

 decrease, but in such cases it is on account of those already present 

 in the grove rather than the supposed great impetus given by the 

 half dozen introduced. Of course the artificial introduction of Scutel- 

 lista in places where they do not occur, or are not well established, 

 should be greatly encouraged. 



The good that might result from the introduction of Scutellista is 

 often rendered negligible because the scale is not in the proper stage 

 to be attacked. With such introductions in most places in southern 

 Cahfornia during July and August, or even later of this year, nothing 

 was left for the Scutelhsta but to perish. At this season all the eggs, 

 or nearly all, had hatched and the parasite will not oviposit on the 

 young scales. This is true also of those already present in the grove 

 and hundreds or thousands must perish unless they find some scale 

 out of season with those that have been attacked. Indeed, this is the 

 most serious matter in the whole Scutellista economy and is a great 

 drawback to their rapid multiplication. This parasite was hardly 

 intended to depend, exclusively on the black scale, where there is a 

 uniform hatch of the insect. Fortunately in most parts of California, 

 and possibly other places where the black scale occurs, there are enough 

 of the so-called ''off hatch" to maintain the parasite until the bulk 

 of the scales are in the proper stage again. 



Life History and Habits 



The egg is pearly white in color, ellipto-cylindrical in shape, with 

 tapering appendage at one end. The length of the body of the egg is 

 about .37 mm. and the appendage about one half that length. The 

 eggs are inserted beneath the scale, usually under the arch at the pos- 

 terior end. The scale need not necessarily be in the egg stage, for 

 eggs have been found both in the field and insectary under scales that 

 had not yet reached the egg-laying stage. The hatching period 

 during the summer months is 4 to 6 days. 



The young larva upon hatching soon begins to feed on the eggs of 

 the scale by sucking out their contents, or, if eggs are not present, it 

 attacks the insect itself. Several cases have been observed where 



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