Bagworm Moth Caterpillars are known to get out of control very quickly. They can damage landscape plants to the point of death. Knowing their life cycle is the key to getting control of an infestation. Keep reading to learn how to get rid of these destructive caterpillars!
What Do Bagworms Eat?
Bagworms are a group of caterpillars with similar feeding hosts. They mainly feed on junipers, cedar, arborvitae, Leyland Cypress and other evergreens with needles instead of leaves. This is not their only food source however.
Their food sources encompass over 100 different types of plants. I have found them feeding on my limelight hydrangeas.
They also have a similar way of defending themselves from predators while they feed and pupate.
Around July and up through August you may see tiny bag like clumps of debris resembling an ice cream cone on the bottom of your plant’s leaves or hanging from needles or branches. Also accompanied by bare spots and leaves stripped down to the vein. This is where the caterpillars hide.
They way the Bagworm Moth Caterpillars protect themselves is by secreting a silken thread they wrap up in and attach various pieces of bark, twigs and leaves, therefore camouflaging themselves from would be predators.
This not only camouflages them from predators, but it also protects them from different types of insecticides making them very hard to get rid of once they reach this stage in life.
Timing is Critical For Bagworm Treatment
The trick to controlling bagworms is seasonal timing. Bagworms can become a huge problem very quickly if not treated at the right time.
Knowing their life cycle and understanding when these stages take place is key to controlling bagworms.
The eggs of the Bagworm Moth hatch in May and the caterpillars begin to feed on your plants. They immediately begin building their bag as soon as they emerge and begin feeding.
As they feed, they attach small pieces of what they are eating to their bag. You can spot a new bagworm if the top part of his bag is still green. You can tell if one has been feeding for a while or is perhaps in the pupal state if the bag is brown and dried.
Bagworm Moth Caterpillar Life Cycle
The Bagworm Moth Caterpillars feed up through August or so. At this time, they will seal up their bags and pupate into moths. After about 4 weeks the males emerge seeking out the female to mate. This is another possible time for treatment.
The female Bagworm Moths remain in their bags and release pheromones to attract the mails. Most females of the species are wingless, I just thought that was an interesting fact. They may never leave their bags or if they do, it is only long enough to mate.
They will lay 500 to 1000 eggs inside their bags which also protects them from everything. One species does not even lay eggs. The fertilized eggs remain inside the female and the caterpillars will emerge from the parent’s body.
To top it off, there is even a species that the eggs will develop even without male fertilization.
So, as you can see, these bagworms are adaptive and can get out of hand rather quickly.
Getting Rid of Bagworm Moth Caterpillars
There are several proven methods to getting bagworm populations under control.
The best and most effective time to treat Bagworm moth Caterpillars is when they first hatch, which is late May to early June in most parts of the country. This will catch them in the time before they’ve made a dense bag to hide in.
The treatment is the same for any other caterpillar. A chemical treatment works best. If you’d like to go organic, you have the option of BT or Spinosad. Keep these life stages and dates in mind when treating.
There is a nematode (Steinernema carpocapse) you can spray on the bags that will get to the caterpillar and devour it inside the bag. Yet again though, timing is critical because you want to get to the female before she lays her eggs.
In the fall, if your population is small, you can actually hand pick the bags off of the tree or shrub that is infected. I do this as well throughout the season as I see them. They are very difficult to see as bags so I always look around the areas where you see the damage to the plant very carefully.
Do not rely on birds to take care of your problem either. Even if a bird swallows the case, the eggs are hard enough to pass through their system unharmed and will be deposited on another tree.
If left unchecked, bagworms can cause substantial damage to your ornamental plants. Their ravenous eating can and will lead to the death of your plant. I recommend taking care of them just as soon as possible.