October, '10] QUAYLE: APHELINUS DIASPIDIS 399 



broadly rounded, contrary to what might be expected, with the first 

 segment disc shaped and firmer than the others, with the small mouth 

 opening in the center. This mouth opening is about 20 yu. in diameter 

 and there are two chitinous spines projecting toward its center in 

 front. These spines are 18 /x in length and 15 /a wide at the base where 

 the muscle attachment occurs. From near the base they suddenly 

 narrow into a sharp pointed spine which is chitinous at tip and brown 

 in color. These are used for piercing the outer wall of the scale and 

 for holding in place while the fluids are sucked from the body. 



The pwpa is dark yellow in color, with ocelli and eyes reddish brown 

 and a similar pigment extending around the anterior margin, and to a 

 less extent about the posterior margin, of the head. Length .75 mm., 

 width .375 mm. The adult appendages, enclosed in their sheaths, 

 lie close to the body on the ventral side. Always accompanying the 

 pupa are from 6 to 10 black or dark brown torpedo hke bodies .125 mm. 

 long and .055 mm. broad, which are evacuations from the digestive 

 tract and are expelled by the larva preliminary to pupation. 



The duration of the egg stage is from 4 to 5 days, of the larval stage 

 12 to 16 days and of the pupal stage 8 to 10 days. The adult^ under 

 nearly normal conditions, usually died in 4 or 5 days. 



This parasite does not always emerge through an exit hole in the 

 scale, but very commonly simply pushes its way out from under the 

 scale. The scale covering seems to be loosened from the surface in 

 most cases so that this means of emergence is comparatively easy. 

 This is further brought about by the movement of the parasite, and 

 also because of the fact that the scale covering is always separated 

 from the insect and has a chance to loosen before the parasite is mature. 

 In case, however, the scale covering is held securely to its resting sur- 

 face the parasite eats out an irregular, rectangular usually, hole in the 

 scale covering just beyond the molted skin, in the case of female scales, 

 and at the posterior third in the case of male scales. The parasite 

 almost invariably is lying on its back as a pupa. Not infrequently 

 two pupse are found under one scale and one case has been observed 

 where there were three. 



The egg is deposited under the scale covering, but either on the 

 upper or lower side of the insect itself, most commonly on the lower. 

 It is not inserted within the body of the scale insect. Prehminary to 

 oviposition a thorough examination is made of the scale by alternately 

 tapping with the antennae from the center of the scale to the periphery. 

 Upon reaching the edge of the scale a rapid backward movement is 

 made at the same time turning sHghtly around so that the entire 



1 The adult of this insect has been described by Howard in the Ann. Rep. U. S. D. A. 

 for 1880. 



