Adults are rounded beetles that vary from yellow to bronze. Each wing cover has eight black spots arranged in three rows. Adults vary from 1/4 to 1/3 inch long and are about 1/4 inch wide. Larvae are yellow, oval and covered with branched spines. Full grown larvae are about 1/3 inch long. Pupae are also yellow and are similar in appearance to larvae, except that the pupae are a resting stage firmly attached to the leaf.
Young larvae feed on the underside of the leaf while older larvae eat through the leaf leaving only the veins. Tender leaf tissue is preferred but pod and stem damage may occur after the leaves become tough.
Treat for Mexican bean beetles according to defoliation guidelines in Table 2 or the population thresholds listed below.
GROWTH STAGE--NUMBER OF MBB PER 4 ROW FT TO JUSTIFY CONTROL
Seedling; 3 adults
Prebloom; 20 adults and larvae
Bloom; 16 adults and larvae
Pod Set; 16 adults and larvae
| Insecticide | Rate per Acre | Days to Harvest/Forage |
|---|---|---|
Ambush |
3.2 to 6.4 fl oz |
60 (Grain) Do not graze or harvest for hay |
Asana XL |
2.9 to 5.8 fl oz |
21 (Grain) Do not feed or graze livestock |
Baythroid 2 (cyfluthrin) |
1.6 to 2.8 fl oz |
45 (Grain & feeding dry vines) 15 (Green forage) |
Dimilin 25 W (diflubenzuron) |
2 to 4 oz |
21 (Grain) Do not feed or graze livestock |
Fury |
3.0 to 4.3 fl oz |
21(Grain) Do not feed or graze livestock |
Lannate WSP |
1/4 to 1/2 lb |
14 (Grain, 3 Forage, 12 Hay |
Larvin 3.2 AF |
18 to 30 fl oz |
28 (Grain) Do not feed forage, hay or straw |
Lorsban 4 E |
1/2 to 1 pts |
28 (Grain) Do not feed or graze livestock |
Mustang Max |
2.8 to 4.0 fl oz |
21(Grain) Do not feed or graze livestock |
Penncap M(methyl parathion) |
2 to 3 pts |
20 (Harvest or grazing) |
Pounce 3.2 EC |
2 to 4 fl oz |
60 (Grain) Do not feed or graze livestock |
Sevin 80 |
5/8 to 1-1/4 lb |
21 (Dry beans or hay) 14 (Graze or forage) |
Warrior |
1.92 to 3.2 fl oz |
45 (Grain) Do not feed or graze livestock |