95' 



BUG VS. BUG. 



49 



this pest wholly under control. In a report on scale insects and their 

 parasites. Professor Comstock says of this insect : 



This is one of the most interesting parasites, both structurally and economically, 

 which we have discussed in this paper. It lives upon the destructive black scale, and 

 so abundant is it in certain regions that upon more than one tree at least seventy-five 

 per cent of the scales appeared to be parasitized. In no locality was the black scale 

 found without this attendant destroyer. 



The female parasite pierces the body of the female bark-louse and deposits probably 

 but a single egg. At all events but a single parasitic larva has ever been found upon 

 a single scale. The larva of the parasite feeds upon the eggs and the young of the 

 Lecanium, and, also, later upon the mother herself. When full grown it is about 0.15 

 inch long, broad, spindle-shaped, somewhat more pointed at the anterior than at the 

 posterior end of the body. Its color is clear white, the contents of the alimentary 

 canal, however, often showing through and giving it a blackish tinge. This larva 

 transforms to a whitish pupa, which soon turns black. The adult parasite makes 

 its exit through a round hole which it cuts in the back of the scale. 



Hymeneyrtus erawii, Ashmead. This is an Australian insect, and 

 is one of the very effective internal parasites of the black scale in that 

 country. It was introduced into California by Mr. George Compere, 

 and has been reported as doing very good work in the districts where it 

 lias become established. 



Aspidiotophagus citrinus, greatly 

 enlarged. 



Aspidiotophagus citrinus, Craw. (Plate III, Figs. I, la. See Fig. 12.) 

 The internal parasite of the yel- 

 low scale (Chrysomphalus [As- 

 pidiotus) citrinus) and the San 

 Jose scale (Aspidiotus pernici- 

 osus). The former scale was at 

 one time as great a source of 

 trouble to the orange-growers of 

 southern California as the red 

 scale (Chrysomphalus [Aspid- 

 iotus] aurantii) is now. It fairly 

 covered the citrus trees, reduced 

 the quantity of fruit, and destroyed its quality. Every effort was made 

 by artificial means to resist its attacks, but these were unavailing. 

 Finally it was discovered that there was some natural check at work, 

 and investigation discovered this little internal parasite. Instructions 

 were at once given to the orange-growers to stop spraying for the yellow 

 scale and to give this little friend a chance to increase. This advice 

 was followed, and in a very short time the yellow scale disappeared 

 from that section and it has not since been regarded as a pest, although 

 no other means have been taken to check it. Mr. Craw has bred this 

 parasite from yellow scale upon imported trees from Japan. Mr. Mar- 

 la tt bred it in numbers from San Jose scale in Japan. It is also one of 

 our best cheeks for the same scale in California. 



