HANDBOOK ON INSECT ENEMIES OF FLOWERS AND SHRUBS 23 



Peony Scale 



In the South the stems of azalea may 

 become infested with the peony scale 

 (Pseudaonidia paeoniae (Ckll.)). When 

 numerous these tiny sucking insects 

 weaken the plants, or they may kill 

 them if there is a continuous heavy 

 infestation. On azalea the thin bark 

 usually grows over the insects, leaving 

 small "bumps," or swellings, on the 

 bark surface. If these bark swellings 

 are opened, the circular, convex, gray- 

 ish-brown scale, about Mo inch in diam- 

 eter, may be found. When the insect 

 is removed, a thin layer of whitish wax 

 usually remains, giving the depression 

 in the bark the appearance of a whitish 

 scar (fig. 36). In the Southern States 

 the young scale insects start hatching 

 about the last of March and continue 

 to hatch for over a month. The young 

 attach themselves to the bark and re- 

 main exposed for about 4 weeks before 



the bark covers them. Spraying for 

 the young stages must therefore be 

 carried out during this period of ex- 

 posure. Apparently only one genera- 

 tion of the insect occurs annually. 

 Although this scale occasionally attacks 

 camellia and a few other woody plants, 

 it is not covered by bark swellings and 

 is usually not so serious on such plants. 

 Treatment. — About 10 days or 2 

 weeks after the young have begun 

 hatching, spray the stems and branches 

 with a white-oil en\ulsion, diluted to 

 contain 2 percent of oil (p. 100), and 

 make a second application about 3 weeks 

 later; or make three applications at 

 intervals of 2 weeks, to cover the 

 hatching period. 



Azalea Leaf Miner 



The azalea leaf miner {Gracilaria 

 azaleella Brants) is a small yellowish 

 caterpillar, about half an inch long when 

 full-grown. Until nearly half-grown 

 it mines inside the azalea leaves, but 

 after this it comes out and folds over the 

 tip or margin of the leaf (fig. 37) and 

 feeds on the surface within this fold. 

 The mined and skeletonized leaves turn 

 yellow and drop. The small moths, 

 yellow with purplish markings, deposit 

 their eggs on the leaves. This insect is 

 more common in greenhouses but occa- 

 sionally injures outside plants. 



Treatment. — Same as for the green- 

 house leaf tier (p. 5). 



Figure 36. — Azalea stem infested with 

 the peony scale and stem showing 

 whitish scars where scales have been 

 removed. Slightly enlarged. 



Figure 37. — Azalea leaves folded at tip 

 and margin by the azalea leaf miner. 

 Young caterpillar on leaf at left. 

 Slightly enlarged. 



