Total # of western bean cutworm caught in traps in each monitored county, Iowa and
Illinois, 2005
1004
2765
188
289
231
363
628
760
540
97 317
495 220
2010
1253
1369 1037 989
677
2040
4590 2307
2107
3753 727 513
971
421
885
427
4940
288
134
3736
2233
326
219
118
420 662
48 230 207
32
232
502
25
193
186 216
62
33
76
54
107
12
2 17
1
1
2
60
11
15
1
9
148
1
27
35
3
21 14
45
1
11
16
16
1
1
8
1
1

• Check 20 plants in at least 5 random locations in each field
–Examine upper surfaces of plant leaves for egg masses and/or larvae
–Examine tassels for larvae before pollen shed
• Consider treatment when 8% of plants have eggs masses and/or larvae
–If larvae have hatched, treat when 95% of tassels have emerged, but before larvae enter the silks
–If larvae have not hatched and corn plants have tasseled, time treatment to coincide with hatch of larvae

Newly hatched larvae feed on leaves, tassels, and silks
After pollination, larvae feed on developing kernels
Injury predisposes the ear to fungal and mold pathogens

M. Rice, Iowa State University Western Bean Cutworm
Lifecycle
U. of Nebraska-Lincoln
M. Rice, Iowa State University
U. of Nebraska-Lincoln