These unique structures are bagworms. If you haven't already, take a few moments and scout your trees to see if you have any bagworms.
Bagworms are caterpillars that live inside spindle-shaped bags which they construct to protect themselves against birds and other enemies. These bags often go unnoticed as they are made up of silken threads and bits of leaves, allowing them to blend in with the tree. As the bagworm gets larger, it is less susceptible to insecticide. Eggs hatch from old bags left from previous years as new bags are created by other bagworms.
Each female bagworm can produce more than 1,000 bagworms. Female bagworms are wingless and never leave the bag while the male bagworm is winged and travels to fertilize the eggs of the female. Eggs stay in the female bags over winter to start the process the next year. There is only one generation of bagworms each year, unlike many other insects which have multiple generations each year.
Once the caterpillars are hatched, there are two control options. The best scenario is to spray a biorational insecticide. A biorational insecticide will kill only the caterpillars. There are several beneficial insects on most trees that feed on scales, spider mites and other harmful insects that should survive an application of a biorational insecticide. These biorational insecticides though are most effective when applied to worms that are very small. Two weeks after application, you should check your trees again to see if any live bagworms are present to determine if re-treatment is needed.
If you have waited too long and the biorational insecticide either won't work or isn't available, then the second option is a rescue insecticide that will kill most of the insects associated with the tree. There is no benefit to spraying nearly adult bagworms in late July and August. In fact, doing so may kill beneficial insects and make things worse. You can obtain a list of potential insecticides to use by obtaining a copy of the Purdue Extension publication, E-27, titled, "Bagworms." Please realize that when using any type of insecticide it is important that you read and follow all label instructions.
If you don't want to use any insecticide, but still want some control over the bagworms, then you can spend time outside hand pulling the bagworms off your trees. Once you have them pulled off, you can simply dispose of them in a bucket of soapy water. For more information on bagworms, check out Purdue Extension publication, E-27, titled, "Bagworms." You can obtain a free copy of it by contacting your local Purdue Extension Office or going online at http://extension.entm.purdue.edu/publica....
As always, if you have any questions or would like information on any agriculture, horticulture, or natural resource topic, then please contact your local Purdue Extension Office at 448-9041 in Clay County or 812-829-5020 in Owen County or reach me directly at firstname.lastname@example.org.
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Upcoming opportunities available to you through Purdue Extension include:
* July 15 -- Clay County Open Class Projects due,
* July 16 -- Owen County Open Class Flowers are entered,
* July 16-23 -- Clay County 4-H Fair,
* July 17-24 -- Owen County 4-H Fair,
* July 19 -- Clay County Farm Bureau, Inc., Flower Show, Clay County Fair,
* July 19 -- Specialty Flower Contest, sponsored by the Owen County Garden Club at the Owen County Fair,
* July 21 -- Owen County Conservationist Class, 6:30-7:30 p.m., Owen County Library, and
* July 30 -- Hoosier Riverwatch Certification Workshop: Adopt-A-Stream, Bloomington.