December, '10] QUAYLE; SCUTELLISTA CYANEA 449 



the larva had grown to considerable size under a scale that had not 

 yet laid eggs. It is not, therefore, strictly an egg feeder, as generally 

 supposed, but of course eggs constitute the normal food. Larvae 

 have been reared from the Soft Brown scale {Coccus hesperidum) in 

 which cases no eggs were consumed for this scale laj^s no eggs. Larvae 

 have also been seen feeding on others of its kind. This cannibalistic 

 habit must be rather common for in nature cases must often occur 

 where several eggs are deposited under the same scale. This is not 

 usually done by the same insect but by different individuals, as ex- 

 plained later. 



The full grown larva preliminary to pupation hollows out a cell 

 in the old egg skins and mats them together more or less with a small 

 amount of silk. Strands of silk are also frequently, or usually, spun 

 from the twig to the inner edge of the scale. Whether this is done in 

 an effort to enclose itself on all sides with a small amount of silk, or 

 whether it is an instinctive provision to assure the old scale adhering 

 to the twig during pupal life, or both may only be conjectured. But 

 it is a common conclusion that old scales harboring Scutellista pupae 

 are not lifted from the twig so readily as those not parasitized. Black 

 scales that have been parasitized by Scutellista are more likely to 

 remain longer on the tree than those that are not. These may remain 

 on the tree for two or three years in many parts of Southern Cali- 

 fornia w^here there is but little rain or wand to dislodge them. This 

 fact is not often taken into consideration in estimating the amount of 

 pajasitization, so that those scales with exit holes increase with each 

 year's infestation, while those without exit holes are more likely to 

 drop off. 



The amount of food consumed or the number of eggs of the scale 

 necessary to bring the larva to maturity varies greatly. A scale has 

 not jet been found too small to have a Scutellista pupa. The smallest 

 mature black scale has been found to be less than one half the size 

 of the largest. The smallest may have a maximum of 500 eggs and 

 the largest from 2,700 to 3,000. The size of the mature larva varies 

 greatly, according to the abundance of eggs, and likewise the adult. 

 Males, of course, are much smaller than the females and there seems 

 to be a preponderance of males in the smaller scales. No eggs hatch 

 in the case of the smaller numbers of eggs, but several hundred may 

 hatch in the case of the larger numbers. The length of the larval 

 period varies from 16 to 21 days during the summer season. 



The mature larva is white in color, with the darker gray of the 

 digestive tract showing through the body wall in some of the speci- 

 mens. The average size of the full grown larva is about 3 mm. and 

 the width about 1 mm. It is broadest at the head end, while there 



