October, "21] Campbell & nixon: mechanical collectors 401 



foliage; while on beans injury is to foliage, blossoms and pods. In a 

 number of. bean fields examined, when the leaves, blossoms and young 

 pods had been injured, less than 50 per cent of the pods on a plant had 

 developed. On many plants, especially near the edges of the field, only 

 one or two pods were left. A typical severely dam.aged plant showed the 

 foliage badly eaten and only one pod developed, while a typical un- 

 damaged plant from the same field had eighteen well developed pods. 

 Often pods are found with large holes eaten in them, rendering the beans 

 unfit for market. In several fields of wax beans, a number of counts 

 were m.ade, which showed that the percentage of injured pods ran as 

 high as 60 on some plants, while the average loss for the fields was 28 

 per cent. 



Remedies for this pest have been rather unsatisfactory'. The use of 

 an arsenical- spray has been unsuccessful in that it kills only a small per- 

 centage of insects. Repellents have also been of little value. 



While walking through a field of }'Oung cucumbers which was being 

 damaged by Diabroticas, it was noticed that when the beetles were 

 disturbed, m.any flew up, usually taking a course close to the ground. 

 This suggested the idea that perhaps such a m.achine as a hopper-dozer 

 would catch many of these low-flying insects. Accordingly it was tried 

 out. A board, 1" x 12", fifteen feet long, was fastened on a ]Dair of 

 runners, 2" x S" x 5'. These runners were placed 5 feet apart. As the 

 bean rows were 30 inches apart, the board would cover six rows at a time, 

 two between the runners, and two on each side. To the back edge of the 

 board a fram.ework three feet high was nailed, to which a strip of canvas 

 was tacked. The upper surface of the board, and the front side of the 

 canvas were smeared with a thin layer of tangle-foot. This apparatus 

 was drawn across the field by a horse. The lower board struck just a 

 little below the tops of the plants in the rows. It was tried several times 

 but did not prove the hoped-for success. The beetles, on rising, would 

 fiy just ahead of the canvas, or rise up and fly over the top. Even with a 

 hood extending 30 inches forward from the top of the canvas, only 1800 

 beetles per acre were caught.^ 



Then a galvanized iron pan, 15 feet long by one foot wide by one inch 

 deep, and properly braced along the back and sides, was substituted for 

 the board. The pan was partially filled with an oil heavy enough to 

 avoid slopping over. The pan rested low enough on the runners so 

 that in going along the rows it struck about two inches below the tops of 

 the plants. When the pan struck the plants, many beetles were shaken 

 loose and thrown back into the oil. In fact, a majority of the catch was 



'Also 2.50 tarnished plant-bugs {Lygiis pratensis L.) and 1(X) lady birds, mostly 

 Hippodamia convergens Guer. / 



