THE LONG SCALE OF THE ORANGE 23 



behind. This scattering in early broods confuses the succeeding ones 

 and renders it impossible to assign to each an exact season or in- 

 variable duration. But although the limits of each brood cannot be 

 exactly defined, the general progress in development may be known at 

 any time by the condition of the majority of the scales. 



Thus there are times when the number of migrating young reaches a 

 maximum, and the application of remedies then proves particularly 

 effective. 



Three such periods occur: The first in spring, usually in March, but 

 sometimes extending into April; the second in June or July; the third 

 in September or October. During the winter months, if the season is 

 a mild one, there is a fourth, very irregular brood beginning in January 

 and continuing through this and the following month. The spring brood 

 that follows is greatly confused. In cold and rainy winters the hatch- 

 ing process is retarded, and the appearance of the Iarva3 on the return 

 of warm weather is more nearly simultaneous than in ordinary seasons. 



Parasites. Upon closely examining a branch or leaf infested with 

 scales of Mytilaspis gloverii, there will always be found a certain num- 

 ber which have through their upper surface a small, round hole. The 

 scales thus perforated are invariably females which have not quite com- 

 pleted their growth. They are empty or occupied by mites or other in- 

 truders, and the only trace of the original inhabitant which they con- 

 tain is its dry, distended skin ; this is also pierced with a round hole, 

 placed directly beneath the one in the outer shell. 



These are the exit holes of Hymenopterous parasites, the most effect- 

 ive enemies of the Scale-insect, and which, after destroying the maker 

 of the scale, and after completing their own transformations in its room, 

 have eaten their way through its skin and its shell, appearing finally as 

 minute four-winged flies, both male and female. 



The female parasite, when seeking to deposit her eggs, probes about 

 the edges of the scale in order to find, if possible, an open crevice through 

 which to insert her slender ovipositor. Failing in this she bores directly 

 through the scale, using her ovipositor as a drill, and in this way inserts 

 within the body of the Coccid a single egg. 



The footless grub that hatches from this egg lives within the body of 

 the Scale-insect and gradually consumes it. When nothing is left but 

 the empty skin of its host the little parasite, now swollen to an almost 

 globular form, transforms first to a pupa, and. then to the perfect fly, 

 which at last makes its appearance through a hole eaten in the walls 

 that surround it. 



Several distinct species of these minute parasites attack the Long 

 Scale. They are about yf^ inch in length, with an expanse of wing 

 equal to nearly twice their length. The head is large, with large com- 

 pound eyes, and three minute simple eyes (ocelli) like jewels set upon 

 its vertex. The body is rather short and thick. The wings are trans- 

 parent and beautifully iridescent ; they are strengthened for a portion of 



