Do Your Trees Have a Bagworm Problem? Here’s how to Treat It! 🌲

If you begin to notice damage to your trees, then take a closer look. Upon closer inspection you may discover that what you thought were pinecones are actually the cocoon-like sacks of the bagworm. Bagworms can damage and kill your trees, so it’s important to know the bagworm’s life cycle so that you can prevent and treat appropriately.

So we’ve got good news and bad news.

The good news:

You can treat bagworms with pesticides and if you see the sacks on your trees, they can be removed.

The bad news:

The time to apply pesticide to prevent these suckers has already passed for this year, and now the most effective treatment is to manually remove the sacks and burn or drown them. I know. EWW. 😝

Just what the heck are bagworms, anyway?

Bagworms begin as black larvae that feed on your trees – especially evergreens like cedar, spruce, juniper and arborvitae – before they emerge as black moths. They can be deadly to those coniferous trees that don’t lose their leaves in the wintertime.

How do you identify a bagworm problem in the fall and winter?

The best way to identify a bagworm problem is to closely examine your trees. Bagworms will create brown sacks that hold around 1000 eggs! These 1.5 – 2 inch sacks will camouflage themselves as pinecones, so you may have to do some close inspection to determine which is which. It’s a little easier to deduce on your coniferous trees in the winter since the brown cocoons are in more contrast against the green needles.

What is the  lifecycle of the bagworm moth?

The lifecycle of a bagworm is important to understand in order to treat or prevent the problem. Here’s the short story:

  • September/October: The males are attracted to the hormones expelled by the females and will travel to their bag where she will lay all those eggs.
  • November – April: The bagworm eggs will spend the winter hibernating in the sacks.
  • May: The eggs hatch in May and will begin munching on your trees. THIS is the time to spray properly with pesticides or other treatments.
  • May – August: Bagworms continue to feed on your trees until August when they will begin constructing more brown silky sacks to lay their eggs.

How do I get rid of bagworms?

Depending on the time of year, here are the 2 most common things you can do to get rid of your pesky bagworm problem and save your trees:

  • May is the month for insecticide sprays and bacteria treatments.

You can spray to treat bagworms, but it has to be done in May once the eggs have hatched. If you don’t want to go the insecticide route, you can also try Bacillus thuringiensis (BT), a bacteria that kills certain insects such as the bagworm but won’t hurt you or your pets. Visit us here at Stockslagers next spring and we’ll be happy to help you find the right treatment.

  • Pick off the bags and burn or drown them.

Yep, we warned you about this. The best way to decrease the population of bagworms taking residence in your trees is to put on a pair of gloves and pick them off of the trees. If you don’t remove the sacks, they can be blown across your yard and cause your bagworm problem to spread. You can bag them and burn them or place them in a bucket of soapy water and then drain and discard them in a baggie in the garbage. Just please don’t put them in your compost pile!

Bagworms are the worst, but there are steps you can take to control them. We’re happy to answer any of your burning bagworm questions!

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