24 



MISC. PUBLICATION 62 6, U. S. DEPT. OF AGRICULTURE 



Azalea Stem Borer 



The adult beetle of the azalea stem 

 borer (Oberea my ops Hald.) girdles the 

 tips of azalea, rhododendron, and moun- 

 tain-laurel, usually after the spring 

 blooming period. It deposits an egg in 

 the bark below the girdle or between 

 two adjacent girdles. During the first 

 summer the grub bores downward, 

 hollowing out the stem and expelling the 

 'boring dust through a series of small 

 holes in the bark. The following sea- 

 son, in the Northeastern States, the 

 grubs continue down to the roots, and 

 toward fall may cut off some of the stems 

 above the ground. The cylindrical, 

 yellowish beetle is about half an inch 

 long and has two small black spots on 

 the thorax, which is just back of the head. 

 The larva, or grub, is legless, yellowish, 

 and about an inch long when full-grown. 

 It is similar in appearance to the larva 

 of the dogwood twig borer (fig. 65, p. 40). 



Treatment. — Cut off the girdled and 

 wilted tips as soon as they become evi- 

 dent in early summer, making the cut 

 several inches below the girdled portion 

 so as to remove the eggs or newly 

 hatched grubs. If the removal of in- 

 fested stems is delayed until later in the 

 season, care should be taken to cut the 

 stem below the point where the grub is 

 located in the burrow and to destroy 

 these infested parts. 



Other Pests of Azalea 



Rhododendron borer 73 



Spider mites 11 



Black vine weevil 93 



Fuller's rose beetle 44 



BARBERRY 

 Barberry Aphid 



The barberry aphid (Liosomaphis 

 berberidis (Kalt.)) is a small yellowish- 

 green aphid that attacks barberry and 

 Oregon grape. It is usually found in 

 groups on the under sides of the leaves 

 and tender shoots, where it sucks the 

 gap and weakens the infested portions 

 of the plant. 



Treatment. — See treatment for 

 aphids (p. 9). 



Barberry Webworm 



The barberry webworm (Omphalocera 

 dentosa Grote) webs together the leaves 

 and twigs of barberry. From within 

 these web nests the caterpillars feed on 

 the leaves. The feeding and webbing 

 usually start after midsummer, and the 

 unsightly nests often remain on the 



bushes during the winter. The cater- 

 pillar is blackish with white spots, and 

 when full-grown is nearly 1 l A inches long. 

 Apparently it spends the winter in the 

 soil and transforms to a moth the 

 following summer. 



Treatment. — Spray the foliage with 

 lead arsenate or paris green when the 

 young caterpillars begin feeding. Spray- 

 ing or dusting with a combination of 

 derris and pyrethrum, as suggested for 

 the greenhouse leaf tier (p. 5), would 

 probably be effective if done thoroughly 

 while the caterpillars are small. 



Other Pests of Barberry 



Page 



Eight-spotted forester 91 



Greenhouse whitefly 18 



Red spiders 11 



Asiatic garden beetle 21 



BOXWOOD 

 Boxwood Leaf Miner 



The boxwood leaf miner (Monar- 

 thropalpus buxi Lab.) is a very small fly, 

 the larvae or maggots of which feed 

 inside the leaves of boxwood. The 

 mines produced by this feeding appear 

 as blotches or blisters on the lower leaf 

 surface (fig. 38), and when numerous 

 they kill the heavily infested leaves and 

 thus disfigure the plant. The tiny 

 yellowish-orange maggots require a year 

 for development, from the time of 

 hatching in late spring until the follow- 

 ing spring, when they transform to 

 pupae within the mines. The orange- 

 colored, gnatlike flies emerge from the 

 leaves over a period of about 2 weeks, 

 usually starting during the first or 

 second week in May around Washing- 

 ton, D. C, depending on the lateness of 

 the season, and deposit their eggs in the 

 new leaf tissue. Emergence would 

 start earlier farther south and later in 

 States to the north. 



Treatment.— Start spraying as soon 

 as the flies begin to emerge in the spring, 

 using a spray composed of 1 gallon of 

 cheap molasses, 5 gallons of water, and 

 10 teaspoonfuls of nicotine sulfate. 

 Repeat the spraying every 3 or 4 days, 

 or as often as necessary to keep both 

 surfaces of the foliage thoroughly sticky 

 during the flight period of about 2 weeks, 

 thus sticking the delicate flies to the 

 leaves. Spraying at other seasons of the 

 year has not been successful. Trim- 

 ming back part of the new growth in 

 late spring will eliminate some of the 

 newly infested leaves and permit addi- 

 tional growth later which will not 

 become infested. 



