398 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



to air passage if they are at all soft and springy. It is equally notice- 

 able that the paper samples transmitted very little, if any, air. 



These results suggest that in the construction of fumigation boxes, 

 we should depend for gas-tightness upon heavy paper, with the edges 

 and overlappings securely sealed, as by gluing, more than upon the 

 quality of lumber, the tightness of the joints, or even a finishing coat, 

 with any material which we have yet tested for resistance to carbon 

 di-sulfid vapor. With hydrocyanic gas, there will be less difficulty 

 because of its lack of the solvent power possessed by the carbon di-sulfid. 



APHELINUS DIASPIDIS HOWARD 

 By H. J. QuAYLE 



This chalcid (Aphelinus diaspidis Howard) is by far the commonest 

 parasite of the red or orange scale {Chrysomphalus aurantii Mask.) 

 in California; in fact, it is the only one of any economic significance. 

 It may be found throughout the citrus belt of southern California, 

 and, while in some places on trees badly infested with the red scale, it 

 may seem rather common, it cannot be counted a very important 

 control factor, since the maximum parasitization found thus far has 

 not exceeded five per cent. 



This insect is commonly spoken of as an internal parasite, yet 

 strictly speaking, so far as the scale insect itself is concerned, it is an 

 external parasite. That is, while it may be under the scale covering, 

 it is not within the body of the scale itself like those of the Soft Brown 

 or Hemispherical Scales, or the various parasites that are entirely 

 surrounded by the body tissues of their host. 



The egg is yellowish white in color, ovate in form, measuring .16 

 mm. long and .96 mm. wide. There is a conspicuous micropyle 

 projecting from the narrower end and also attached to this a short 

 stalk that is doubled back on itself. The chorion is smooth, with 

 spherical granular bodies showing through with transmitted light. 



The larva when full grown appears as a more or less structureless 

 top-shaped globule, measuring, when segments are normally extended, 

 .75 mm, long and .5 mm. wide. It tapers considerably more toward 

 the posterior end, and there is a. slight difference between the dorsal 

 and ventral surfaces. The distance between the upper and lower 

 surfaces is a httle less than the width of the body so that there is some 

 indication of flatness. The color is glossy white, with the food in the 

 digestive tract showing distinctly yellow, oval in shape and measuring 

 about one half the dimensions of the larvae itself. There are 14 in- 

 distinct segments including the button at the tip. The head end is 



