In the vegetable garden this destructive garden pest is found on all types of beans both bush and climbing, along with cowpea, corn and peanuts.
The eggs of this vegetable garden pest are lemon-shaped and orange. The larvae is basically whitish with both ends colored dark brown and looks practically the same as corn root-worm. It has six tiny legs near the head. The pupa is soft-bodied and white.
All stages of this pest are a problem to both commercial and home gardeners.
Adult beetles can vary greatly in color giving the impression you are dealing with a host of different bugs.
Typically they have six black spots, three on each wing cover and a distinct black band surrounds the outer edge of the wing covering.
Cream Color With Spots
However there are many of them that don't have any spots at all.
Reddish No Spots
Cream-brown Color With No spots
The one tell tale marking that all these beetles do have in common is a black, triangular-shaped mark on the forward margin of the wings, directly behind the neck area . Easily seen here on these two beetles without any other markings.
Often, when disturbed, the bean beetle will folds its legs and falls to the ground, where it may remain motionless for a while making them very hard to spot.
Controlling bean beetles is most effective when they are still in their immature stages. Removal of visible eggs and applications of Beneficial Nematodes to control larvae should be done early in the growing season before damage appears.
Close observation is needed to spot eggs laid on foliage or larvae actively feeding on foliage. At this stage you can use a Neem Oil product to kill them before they hatch. Neem acts as a contact insecticide, so it has limited residual impact. It will need to be reapplied after top watering or rainfall.
Fight fire with fire, generalist predators such as Ladybugs, Mantis, or Spined Soldier Bugs can also be released to control foliage feeding larvae.
The seven spotted lady bug is one of many members of that family that will feast on the beetle larvae.
The praying mantis is another relentless predator of beetle larvae, as well as many other vegetable garden pests.