October, '21] Campbell & xixon: mechanical collectors 403 



With the above apparatus a man and one horse easily covered thirty 

 acres per day, at a ver>- low cost per acre. As one farmer expressed it, 

 each beetle if left in the field, will destroy at least one blossom or pod, 

 besides doing some damage to the foliage, and by catching 3500 beetles, 

 there will be at least 3500 more pods to the acre, which is approximately 

 35 pounds. 



Of course, such a machine failed to catch many of the beetles the first 

 time, but the low cost of the operation permitted going over the field 

 once or twice a week for several weeks which greatly reduced the amount 

 of damage to the crop. It is known that when food is plentiful, the 

 beetles do not travel far, but remain near their favorite food plant. ^ So 

 with plenty of food, as is usually the case, a reinfestation of the cleaned 

 field would be unlikely. 



The best time to catch the beetles was found to be about 10 a.m. and 

 3 p.m., and a quiet, cool day w^as better than a hot, windy one. The 

 present cost of the apparatus described above is. S3. 50 for the galvanized 

 iron trough, $2.25 for the wire screen, and $1.25 for the lumber, making a 

 total cost of $7.00 for material. The catcher can be easily and quickly 

 m.ade. 



Such a machine would be serviceable for capturing the beetles infest- 

 ing any low-growing crop, such as beans, beets, cucumbers, etc., grown 

 in rows, and also such crops as alfalfa up to the time it is about half 

 grown. 



The western striped cucumber beetle {Diabrotica trivatatta Mann.) 

 also causes extensive damage. This species, however, confines its feed- 

 ing largely to cucimiber, squash and related plants, often causing almost 

 com.plete defoliation. It also feeds on the stems of young plants which 

 many times results in killing the plants outright. Later blossoms and 

 fruit m.ay be badly damaged. 



In 1917 and 1918 the pumpkins and squashes grown by one of the 

 canning companies were severely dam.aged by cucumber beetles. Both 

 trivitatta and soror were present, thotfgh the form.er predominated. 

 Since the plants were in hills the machine described above was not entire- 

 ly suitable, but a similar machine on the same general plan was developed 

 which proved entirely satisfactory^ The principle of this Diabrotica 

 catcher was as follows: Cover the entire plant with an opaque box, with 

 light showing only from one side. Cover this side with a tilted wire 

 screen, under which is an oil trough. Place the catcher over the plants 

 and the beetles being aroused, fly toward the light, hit the screen and fall 



"Journal Econ. Ent. Vol. 8. No. 6, pp. 517-18, by R. A. Sell. 



