270 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



the sticky boards, and perish. In this way the beetles can be col- 

 lected from the plants, and the amazing results are due apparently 

 solely to the growth the seedhngs make when their leaf surface is 

 entirely unharmed. 



The trap is easily made from light wood ; the illustration (fig. 56) 

 and the following instructions show the details of its construction : — 



To a frame made of six pieces of half-inch deal 20 inches 

 long two pieces of thin board (20 inches by 5 inches) are fixed so as to 

 slope outwards and upwards on the sides of the frame. These sloping 

 boards are held apart by a cross-bar and an end piece, so as to have 

 four clear inches between them at the bottom. The two bottom 

 outer pieces of the frame are made half-inch deeper than the inner 

 pieces, the whole trap riding on the outer pair as a sledge on runners. 

 The ends are rounded off to allow free running. The sloping boards, 

 the end pieces facing them, and the cross piece between them are 

 greased. From the cross-bar between the sloping pieces hangs a loop 

 of stout string, and strings four feet long are attached to the front top 

 corners. 



If the trap is drawn down each row of turnips so that the young 

 plants pass under the cross-bar and are brushed by the string 

 loop, the beetles leap up and alight on the sticky boards. There they 

 perish. 



If made of deal, this apparatus is so Hght that a child can draw it 

 along the rows ; it is better for two persons to draw the trap, and for 

 them to walk a few feet away on each side, so that the beetles are not 

 disturbed until the sticky boards reach them. If two persons are 

 not available, one can work the trap, drawing it with outstretched arm, 

 and walking so that the shadow falls on rows already done. 



The cost of the trap Hes between two shillings and half-a-crown, 

 and steps were at once taken to make the trap available to those who 

 wished to purchase it ready-made. 



In the experiments vaseline was first used, but was found to melt 

 too readily under the hot sun ; other substances used with success 

 were Morlar Hop wash (the pure undiluted wash), Wood & Sons' 

 smearing grease, and black currant mite grease. Many other sub- 

 stances may probably be used, and it is only important to have a 

 material that remains sticky and is not so tacky as to let the beetles 

 jump off before they sink into it. 



The trap as figured here does one row at a time : obviously a trap 

 of the size described is suitable only for garden use, but the principle 

 can probably be appHed to field use by making a multiple trap based 

 on the width of one of the drills. We have as yet had no opportunity 

 of testing any pattern on a larger field scale. 



A remedy in use against Turnip-Fly has been to drag a tarred board 

 over the field, but this is open to the objections that it damages the 

 plants and that the tar soon becomes covered with dust and earth. 

 The sloping board principle, with runners, does away with both these 

 objections. 



