Bagworms Could be a Problem in 2021

While we have had an ongoing battle with bagworms for several years and have reduced their numbers significantly in southeast Nebraska, there are still bagworm infestations in some areas. In 2019, we had one of the worse years for bagworm infestations in southeast Nebraska in recent years. In southeast Nebraska, the larvae emerged over several weeks during the summer, but usually beginning around Memorial Day. With the variable weather we have seen this spring, some warmer and some colder than normal temperatures, it is difficult to predict when bagworm larvae may emerge.  It is important to keep an eye on your evergreen trees this year and watch for infestations of bagworms.  If you had bagworms last year, and have not removed the bagworm bags from your trees earlier this spring, you should check your trees this month and remove those you can easily pick off your trees.

Bagworm eggs usually hatch in late-May to mid-June.  Check your evergreens, for infestations of these young larvae.  They will form a new bag over their bodies.  They start out very small with a 1/8” bag around their bodies, but grow in size and construct a bag 2” long by mid-August.  Bagworm larvae damage the tree by feeding on leaves or needles causing defoliation.  It is best to spray when you see the larvae. If you do see them, there are several types of sprays that can be used for control of the bagworm. If you want to use something natural, BT is effective in controlling bagworms and can be purchased as Dipel from most garden centers.  The small larvae can be controlled chemically by Sevin, Eight, DeltaGard, Orthene or Malathion, among other things.  If you wait until August and the larvae are 2” long and inside their bags, chemical control will be very poor.  You can contact me, Gary Lesoing at Nemaha County Extension office at (402) 274-4755, (402) 274-9639 (cell), email at glesoing2@unl.edu or your local extension office for information about bagworms.  There is also information on the web about bagworms at: https://lancaster.unl.edu/hort/bagworms.shtml

bagwormsGary Lesoing
Extension Educator
Nemaha County
May 2021