32 



MISC. PUBLICATION 6 2 6, U. S. DEPT. OF- AGRICULTURE 



(p. 12). For very tender plants, spray 

 at weekly intervals with nicotine sulfate 

 and soap until the infestation is elimi- 

 nated. This will kill many of the newly 

 hatched young and eventually eliminate 

 the insects. Less tender plants may be 

 sprayed with a while-oil emulsion, with 

 the oil and nicotine combined (p. 101\ or 

 with thiocyanate. The spray should be 

 applied with as much force as the plants 

 will stand. It is advisable, however, to 

 rinse the plants with water an hour or 

 two after spraying with thiocyanate to 

 avoid any possible spray injury. Syring- 

 ing the infested plants frequently, 

 especially the hardier ones, with water 

 under considerable pressure is usually 

 effective in reducing an infestation. 

 Before spraying is undertaken all dead, 

 dying, and heavily infested portions 

 should be removed and destroyed. 



Prevention. — All plants should be 

 carefully examined before they are set 

 out to see that they are free of infesta- 

 tion. 



Greenhouse Orthezia 



Although primarily a pest of plants 

 grown under glass, the greenhouse or- 

 thezia {Orthezia insignis Browne) is a 

 scale insect which is related to the 

 mealybugs and has habits similar to 

 theirs. It feeds on many varieties of 

 bedding plants out of doors, especially in 

 the warmer parts of the country. The 



Figure 52. — Portion of coleus plant in- 

 fested with the greenhouse orthezia. 

 Three times natural size. 



constant sucking of the vital juices 

 weakens the hosts so that they become 

 sickly and sometimes die. Lantana, 

 chrysanthemum, coleus, heliotrope, peri- 

 winkle, petunia, salvia, and verbena are 

 particularly subject to injury. The 

 mature female is pale brown or dark 

 green and is conspicuous because of its 

 waxy marginal fringe and long, white, 

 fluted egg sac (fig. 52) . The length of the 

 insect together with its egg sac is about 

 % inch. All stages are active and settle in 

 colonies on the leaves and stems of the 

 plants. 



Treatment and prevention. — Same 

 as for mealybugs (p. 31). 



Other Pests of Coleus 



Page 



Red spider 11 



Greenhouse whitefly 18 



Yellow woolly bear 3 



COLUMBINE 

 Columbine Borer 



The columbine borer (Papaipema 

 parpurifascia (G. and R.)) attacks the 

 stems and especially the roots of 

 columbine, both cultivated and wild. 

 The caterpillar, or borer, burrows 

 through the stems and fleshy roots, 

 causing the infested plants to wilt or the 

 stems to break easily. Small piles of 

 frass or dark sawdustlike castings near 

 the base of the plants are evidence that 

 the borers are at work. The moth lays 

 her eggs in scattered fashion over the 

 ground late in the summer. The eggs 

 hatch the following April or May, and 

 the tiny larvae soon enter the stems. 

 They first bore in the stems above the 

 ground but later they work their way 

 down to the roots. By July they reach 

 full size, ranging from 1 to 1% inches in 

 length, and have a pinkish cast, resem- 

 bling somewhat the larvae of the iris 

 borer (fig. 85, p. 52). They may usually 

 be found tunneling the main roots at 

 this time. Later the caterpillars trans- 

 form to pupae, and finally to adult 

 moths, which are reddish brown. 



Treatment. — Cut out and burn the 

 infested parts where the insects are at 

 work, whenever practical. Probing the 

 burrows with a fine flexible wire to kill 

 the borers within gives some relief. In- 

 jecting a strong solution of pyrethrum 

 into the burrow in the stem kills such 

 borers as are reached. Carbon disulfide 

 is sometimes used by injecting a tea- 

 spoonful into each of 5 or 6 holes a few 

 inches deep in the soil several inches 

 from the base of the plant. Great care 



