THE BARNACLE SCALE. 59 



form of tho young, clotted over the glossy surfaces of the leaves, fre- 

 quently attract attention, but their numbers are always so greatly re- 

 duced during growth that only three or four per cent, reach tho 

 adult age. 



The thinning-out is not alone the work of euemies and parasites, but is 

 also due to the fact that the lice, when they become gravid, cannot main- 

 tain their hold upon the smooth surface of the leaves. They fall to the 

 ground and perish, being in the latter portion of their lives incapable 

 of free movement and, therefore, unable to reasceud the trees. Tio 

 Orange is not, therefore, adapted to this species of Scale-insect, and is 

 never subject to long-continued or very damaging attacks by it. 



The occurrence of this Bark-louse upon wild plants, in portions of 

 Florida very remote from cultivation, seems to indicate that it is indigen- 

 our, and not imported as supposed by Mr. Ash mead, who, however,con- 

 siders it identical with Ceroplastcs rusci (Linn.), a common European 

 species. Professor Comstock, who has carefully compared the 'Jld 

 World species with our own, remarks that C. floridensis "presents sev- 

 eral marked differences ; the most easily noticeable being the small 

 size of the central plate, and its entire disappearance so early in the life 

 of the insect." 



Parasites. A small Hymenopterous fly has been bred from Cero- 

 plastes floridensis. It is similar in appearance and habits to Encyrtus 

 tlaviis Howard, previously mentioned as preying upon Lecanium hes- 

 peridum.* In his paper on parasites of the Coccidae (Report Comin. 

 Agric. for 1880, p. 3G9), Mr. Howard notices the occurrence of an allied 

 parasite, a species of the genus Tetrastichus, which also remains unde- 

 scribed. 1 



THE BARNACLE SCALE. 



(Ceroplastes cirripediformis Comstock.) 



[Fig. 21.] 



The following account of this somewhat uncommon scale is given by 

 Professor Comstock (Report Commissioner of Agriculture for 1880, 

 p. 333): 



"Adult Female. Average length 5 mm ; width, 4 mm ; height, 4 mm . When 

 naked the color is dark reddish brown; the shape sub-globular, with a 

 strong spine-like projection at the anal end of the body. The waxy 

 covering is dirty white, mottled with several shades of grayish or light 

 brown, and even in the oldest specimens retains the division into plates, 

 although the form is more rounded and the dividing lines by no means 

 as distinct as- at an earlier age. There are visible a large convex dorsal 

 plate, and apparently six lateral, each with a central nucleus; the anal 



*This may be Aphycus ccroplaitis Howard, described in Bulletin 5, Bureau of En- 

 tomology, as bred iroin Ceroplastes artemesice Riley MSS., from Silver City, N. Mex. 



