152 ECONOMIC ENTOMOLOGY 



Nymphs. — Three-one-hundredths inch long, yellowish when full 

 grown; long waxen rods on back of "pupa." Life-cycle about 5 weeks. 



Control. — Fumigate at night with hydrocyanic acid gas Q/^ oz. 

 potassium or sodium cyanide, i fi. oz. sulphuric acid, 3 ii. oz. water, 

 for every 1000 cubic feet of space); spray or wash repeatedly infested 

 leaves with whale-oil soap {i^^ oz. to i gal. water). 



Citrus White Fly {Dialeurodes citri Ashm. = A. citri Riley & 

 Howard). — A most serious pest of oranges and other citrous plants of 

 the South. (Consult Tech. Ser. No. 12, Pt. V and No. 27, Bur. Ent., 

 U. S. Dept. Agr.) 



PsYLLiD^. (Jumping Plant-lice) 



Pear Psylla (Psylla pyricola Fuerst). — A European pest introduced 

 about 1832, and now widely distributed over the Eastern states and 

 Canada. 



Adult. — A dark reddish-brown bug, Hq inch long; abdomen with 

 black bands; wings clear with dark veins and laid roof-Hke over the body; 

 when disturbed it hops and flies away. Eyes bronzy; hibernates on 

 trunk in crevices, etc.; 4-5 generations each year. 



Eggs. — Orange-yellow, minute; 3^^ g irich long, pear-shaped; depos- 

 ited in crevices of bark or along midrib of leaf; hatch in 2-3 weeks. 



Nymphs. — Broadly oval, flattened, yellowish bodies with crimson 

 eyes; later reddish with black markings and conspicuous black wing 

 pads; secrete honey dew; 4-5 moults. 



Natural Enemies. — ^Lady-birds, protracted periods of wet cold 

 weather in spring, and long spells of hot dry weather in summer. 



Control. — Clean cultivation; bark scraped; spraying with Black 

 Leaf 40 ( I pint in 100 gal. water) during warm days in early spring, 

 late fall or after blossoming; spraying with lime-sulphur just before 

 opening of blossoms. 



Bramble Flea -louse {Trioza tripundata Fitch). — Occurs on black- 

 berry, causing curling of the leaves and dwarfing of the shoots. 



Adult. — A small reddish-brown, jumping plant-louse, 3^^ inch long; 

 wings with three yellowish-brown bands. October- May or June. 



Eggs. — ^Light yellow, deposited in June- July on blackberry. 



Nymphs. — Mature in September-October; young nearly pure white' 

 to a greenish white; older nymphs yellowish. ' ' 



