HANDBOOK OX INSECT ENEMIES OF FLOWERS AXD SHRUBS 



45 



der, rose, wandering-jew. and the foliage 

 of various trees. It bores into the rind 

 of oranges. The full-grown caterpillar 

 is a little over half an inch long and 

 varies from greenish white to dark gray. 

 The small adult moth is gray. 



Treatment. — Same as for green- 

 house leaf tier (p. 5). 



Other Pests of Geranium 



Page 



Greenhouse whitefly 18 



Red spiders 11 



Cabbage looper 3 



Corn earworm 29 



Oblique-banded leaf roller 83 



Aphids 9 



Greenhouse leaf tier 5 



Mealybugs 30 



Cottony-cushion scale 71 



Fuller's rose beetle 44 



GLADIOLUS 



Gladiolus Thrips 



The gladiolus thrips (Taeniothrips 

 simplex (Morison)) is at present the 

 worst insect pest of gladiolus. The 

 thrips feeds on the corms while in 

 storage, and the fed-over areas become 

 russeted. The infested leaf sheaths 

 become brown and the leaves '•silvered." 

 and the bud sheaths dry out and appear 

 straw colored. The flowers (fig. 73) 



Figure 73. — Gladiolus thrips injury on 

 flowers. Note bleached areas on 

 petals. 



749493°— 48 4 



have whitish streaks, and in severe cases 

 the spikes never show color but turn 

 brown and appear blighted. The adult 

 thrips is a very tiny insect. It has a 

 brown body and a white band at the 

 base of the featherlike wings. These in- 

 sects (fig. 74) are not often seen unless 

 the plants are carefully examined, be- 

 cause they usually conceal themselves 

 in the leaf sheaths, although they come 

 to the surface to feed under favorable 

 conditions. 





^L*n 



'& 



Figure 74. — Gladiolus thrips: A, Adult 

 male; B, adult female. Twenty times 

 natural size. 



Treatment. — After harvesting the 

 corms, allow them to dry for a month. 

 Then remove the old corms and hulls 

 and treat the clean corms with naph- 

 thalene flakes, using 1 ounce (4% level 

 tablespoonfuls) for every 100 corms, or 

 1 pound (1 quart) for 2,000 corms. For 

 small lots, place corms in a tight paper 

 sack and scatter the flakes among them, 

 then fold over and fasten the top of the 

 bag tightly to retain the fumes. Remove 

 the naphthalene after about 4 to 6 weeks 

 and then store the corms in an insect- 

 free place. This treatment may be used 

 at any time in winter, preferably be- 

 tween November 1 and March 1. In 

 southern and warmer regions, apply the 

 treatment according to the cultural pro- 

 gram but not until corms have dried at 

 least 3 to 4 weeks after digging. Do not 

 use a covered tin can or other tight con- 

 tainer, as the corms will "sweat" and 

 sprout during the treatment and be 

 injured. 



If it is impossible to use naphthalene, 

 the corms may be treated with mercuric 

 chloride, preferably just prior to plant- 

 ing, to avoid the necessity of drying out 

 the- corms if they have to be returned to 

 storage. Use this chemical at the rate of 

 1 ounce to 7 r > gallons of water (1 to 

 1.000). and keep the corms immersed in 

 the dip for 12 to 17 hours. If the corms 

 are peeled, a soaking of 7 hours will 

 suffice. See the caution and further in- 

 structions regarding the use and han- 

 dling of this poison as given on page 102. 



If infestation develops in the garden 



