HANDBOOK OX INSECT ENEMIES OF FLOWERS AND SHRUBS 93 



Water lily Leaf Cutter 



Waterlilies and other aquatic plants 

 are sometimes injured by the water 

 lily leaf cutter {Nymphula obliteralis 

 i Walk.)). The caterpillars cut oval 

 pieces out of the leaves and attach these 

 to the upper surface. At times the 

 pieces are fastened together with silken 

 strands to form flattened, oval cases 

 about % inch in length. These cases 

 serve as protection and are carried about 

 by the caterpillars as they feed. The 

 wind may blow these boatlike cases 

 about the pool and thus spread the in- 

 festation. As a result of the continuous 

 feeding of the caterpillars the leaves are 

 soon reduced to a ragged, rotten mass. 



A closely related species, Nymphula 

 gyralis (Hulst.), injures waterlilies by 

 boring into the stems of leaves and 

 flowers. 



Treatment. — A light infestation of 

 the leaf cutter may be eliminated by 

 gathering and destroying the cases as 

 soon as they are observed. In severe 

 infestations the water level of the pool 

 should be lowered sufficiently to permit 

 dusting the plants with a mixture con- 

 sisting of equal parts by volume of 

 pyrethrum powder and tobacco dust. 

 The application should be repeated 30 

 minutes later, The first application 

 drives the worms out of their conceal- 

 ment and the second one kills them in 

 their unprotected state. Spraying with 

 lead arsenate is also recommended at 

 times. If fish are present in the pool, 

 they should be removed before either 

 of these treatments and not returned 

 until after the water has been changed. 



In the case of the stem-boring species, 

 remove and destroy the infested parts 

 containing the borers. 



YEW, OR TAXUS 

 Black Vine Weevil 



The needles of yew, especially on the 

 innermost branches, are bitten off at 

 the tip along one side, or eaten com- 

 pletely, by the adults of the black vine 

 weevil (Brachyrhinus sulcatus (F.)). 

 The young, white, grublike larvae (fig. 

 157) also feed on the rootlets, and later 

 they girdle or strip the bark from the 

 larger roots. Arborvitae, astilbe, fern 

 (maidenhair), gloxinia, hemlock, prim- 

 rose, rhododendron, tuberous-rooted be- 

 gonia, and wisteria are among the more 

 than 75 other greenhouse and outdoor 

 plants which this pest attacks. Out of 

 doors this insect usually breeds on 

 strawberry, yew, rhododendron, or on 

 weeds such as dandelion or broadleaf 

 plantain. The adult (fig. 158), which 

 749493° — 48 7 



Figure 157. — Larvae, or grubs, of the 

 black vine weevil. About natural 

 size. 



4- 



Figure 158. — Black vine weevil adult. 

 About twice natural size. 



is about % inch long, is black with 

 patches of yellowish hair scattered over 

 the otherwise roughened body. The 

 winter is passed mostly as nearly full- 

 grown larvae or pupae. The wingless 

 adult females emerge in June and July. 

 There is only one generation a year. 



Treatment. — Spray with lead arse- 

 nate late in June or early in July before 

 egg laying begins, or dust with a mix- 

 ture made of equal parts by weight of 

 calcium arsenate and hydrated lime. A 

 poisoned bait made according to the 

 formula given below is also effective 

 when applied early in the evening. 



Bran 5 pounds. 



Molasses 1 pint. 



Calcium arsenate 4 ounces. 



Water 2 quarts. 



The poisoned-bran bait recommended 

 for cutworms may also be effective, 

 although it has not been tested. 



Other Pests of Yew 



Page 



Red spiders 1 1 



Grape mealybug ... 16 



Oleander scale . - 54 



