Leaves riddled with holes are caused by a tiny, shiny black beetle. Learn about flea beetle infestation and damage.
What is it?
Corn flea beetles are beetles which jump in the same manner as fleas, but are unrelated to fleas. Both adult and mature flea beetles can be of harm to the corn plants at various stages of their development. Corn flea beetles are also known to spread the disease known as bacterial wilt which is a prime killer of corn plants.
What does it look like?
Flea beetles are tiny, shiny and a very dark black. Corn flea beetles grow only up to 1/16 inch and they will jump just like fleas when they are disturbed for any reason. Corn plants with flea beetle damage will have holes in their leaves which look almost as if they have been shot they are so riddled with openings. The holes are usually about 1/8 inch in diameter but may join together to form larger openings. The corn flea beetles chew the leaves from the undersides and seedlings are especially susceptible and in many cases whole corn plants can wither, wilt, and die if left untreated, regardless of their stage of development.
How does it manifest?
Corn flea beetles start out as legless whitish grey grubs which have hatched from eggs that have been laid be female flea beetles in the surrounding soil. These legless grubs feed on the roots and undersides of leaves in corn family plants for approximately two to four weeks after they hatch.. After pupating in the soil, corn flea beetles emerge as mature adults and begin the process again feeding for up to two months and reproducing quickly, creating up to four generations of mature flea beetles each growing season. As adult beetles, they chew holes in the leaves, leaving them looking riddled as if by a shotgun. These leaves quickly wither, dry out and die. Adult corn flea beetles may feed for a period of up to two months.
What can you do about it?
When you see the first signs of corn flea beetle damage on leaves in your garden, use an insecticide which contains either carbaryl, pyrethrins, or diazinon to help control these pests. Each time new growth is affected, or you find further damage, repeat the application of the chosen insecticide. You can repeat the treatment safely every seven days if necessary. Additionally, make sure to clear away all plant debris which can harbor insects and eggs which can overwinter.
