32 



tiiicl very natural fears of damage are excited, but as a rule the natural 

 enemies and other causes result in very few of the j'oung reaching the 

 adult stage. This, as shown b}'^ Mr. Hubbard, not only follows the 

 action of parasites, but also is due to the fact that the scale lice as they 



become old and gravid can not maintain 

 their hold on the smooth surface of the 

 lemon or orange leaf and fall to the ground 

 and perish. The citrus plants, therefore, 

 are not especially adapted to this insect 

 and very rarely suffer long or seriously 

 from it. 



The Florida wax scale is three-brooded, 

 development not being very rapid and 

 extending over three or four months. The 

 waxy secretions give an appearance to the 

 3'oung insect of an oval stellate object, the waxy prominences 

 coalescing and disappearing with age. 



Fig. 25. — Florida wax scale (Ceroplas- 

 tesfloridensis) : Groupof scales, illus- 

 trating different stages of growth- 

 enlarged about 4 diameters (origi- 

 nal). 



The Barnacle Scale. 



This insect ( Ceroplastes cirripediformis Comstock — fig, 

 closely allied to the last, has been found in two or 

 three localities in Florida, notably at Jacksonville and 

 in Volusia County, on orange and quince, and also on a 

 species of Eupatorium. It is frequently associated on 

 citrus plants with the Florida wax scale. It has since 

 been found on the same and other food plants on some 

 of the West Indian islands and in Louisiana and Cali- 

 fornia. The barnacle scale is much larger than the 

 Florida wax scale, having an average length of 5 milli- 

 meters and a width of -i millimeters. The waxy cover- 

 ing is a dirty white, mottled with several shades of 

 grayish or light brown, and the division of the waxy 

 excretion into plates is distinct, even to a late age. The 

 development of the insect and secretion of the waxy 

 scale covering is very similar to. that of the last spe- 

 cies described. The barnacle scale is of very little eco- 

 nomic importance, and is mentioned merely because its 

 presence might arouse suspicions of probable injury. 



The Fluted Scale. 



26), which is 



Fig. 26.— Barnacle 

 scale {Ceroplastes 

 cirripedifoi-mis): 

 Group of scales 

 on twig, illustrat- 

 ing different 

 stages of growth 

 — enlarged about 

 2 diameters 

 (original) . 



Of all the scale insects attacking citrus plants, this species {Icerya 

 purchasi Maskell — figs. 27 and 28) is perhaps the most notable, not so 

 much from the damage now occasioned by it as from the problems of 

 control which it has brought to the front and the international charac- 

 ter of the work which it has occasioned. 



172 



