Why Plaster Bagworms Are Targeting Florida and How to Stop Them
Have you ever seen a small, gray-brown worm with hair-like scales and a speckled pattern crawling up the side of your house or interior walls? Don't worry—it's not a dangerous pest. It's probably just a harmless plaster bagworm.
These tiny moths, also known as Phereoeca Uterella, are native to Florida but can be found in other parts of the world too. They measure an average of one inch long and feed on lint, dead insects, and other debris like plant fragments such as coniferous trees, and believe it or not, bits of sand and household debris that they use to craft their webs.
Despite the fact that they don't damage the structure of homes or attack household items indoors, they can cause trouble by getting into places like bedroom closets and cupboards, as this is where they tend to spin their hard webbed shelled silken cocoons. It's in these very cocoons that more than 200 eggs lay dormant throughout the winter, safe inside the protective casing, just waiting for their spring breakfast.
As larvae, plaster bagworms typically cause the most damage. Normally, residents report to us that they see bagworms during this stage of their lifecycle, meaning they report seeing worm-like caterpillars more often than moths. In this article, I'll discuss why these bagworms are so prominent in south-eastern Florida and, ultimately, what you can do about it!
What Are Plaster Bagworms?
Plaster bagworms are a species of moth that typically feed on plant matter and commonly build their cocoons from materials such as sand, lime, twigs, nails, and whatever else is available. This particular species has a rather unique method of using spider webs to inoculate their nests, and the larvae molt the hatched eggs onto a substrate of plaster or other construction materials. They are known to cause considerable damage to structures in tropical climates like Florida.
Life Cycle Details
Plaster bagworms undergo a complete metamorphosis with distinct egg, larval, pupal, and adult stages. Believe it or not, there can be 2-3 overlapping generations per year here in Florida's humid climate.
- The life cycle begins when adult females lay eggs in the fall, depositing 200-300 eggs in a cocoon made of silk and debris.
- The eggs overwinter and hatch in early spring into tiny larvae or caterpillars.
- The larvae feed on dead plant matter and detritus, constructing a portable case or "bag" around themselves made from silk and debris.
- They go through 5-6 molts over 2-3 months, enlarging their bag as they grow.
- The pupal stage lasts about 2 weeks, during which time they undergo metamorphosis inside the bag.
- Adults emerge in late spring/early summer, with a lifespan of around 2 weeks.
- Mated females restart the cycle by laying eggs.
What Do They Look Like?
They are gray with up to four spots on the fore wings and a brush of long, lighter gray hair-like scales along the posterior margin of the hind wings. The antennae are filiform (threadlike), as long as the wings, and are held back over the body. Adults at rest hold their wings tented over the body.
Adult females have a wing span of 10 to 13 mm long, while males are a bit smaller with a wing span of 7 to 9 mm) and are relatively thinner than the females, with a less distinctive wing pattern.
Source: edis.ifas.ufl.edu
Diet Information
Plaster bagworm larvae are detritivores, meaning they feed on dead organic matter like dried leaves, twigs, bark, and other plant debris. They especially seem to prefer materials like Spanish moss, pine straw, wood, and fabrics. The larvae construct their portable bag shelters by webbing together these items as food sources and camouflage. Adults do not feed at all during their short lifespans.
Why Are Plaster Bagworms Targeting Florida?
The subtropical climate in Florida provides an ideal environment for plaster bagworms, who thrive in warm temperatures. Experts suspect that the infestation began when eggs were inadvertently introduced as shipping cargo from somewhere outside of Florida. The typical life cycle of plaster bagworms is completed in roughly three months, allowing them to quickly reproduce and spread across the state with ease from one favorable environment to another.
When Is Bagworm Moth Season in Florida?
Common bagworm larvae usually emerge in late spring and early summer and may disperse through the air using silk threads; some may stay on their host plant if food is available. The caterpillar stage of the Plaster Bagworm could take up to four months, depending on temperature and food source. Adult moths are typically seen from May to October but can sometimes be seen from January to November.
The Florida Bagworm vs Plaster Bagworm
The Florida Bagworm and the Plaster Bagworm have some significant differences. The most noticeable one is their shape: the Plaster Bagworm has a squarish body, while the Florida Bagworm has a more cylindrical body.
The habitat of these two bagworms also differs greatly. The hatching larvae of a Plaster Bagworm is limited to decaying vegetation or terrestrial environments, while the hatching larvae of a Florida Bagworm can make homes in aquatic plants.
In terms of food preferences, both worms prefer to snack on dead plant material or dried mosses, but the Plaster Bagworm will feed on living fungi and pollen, too!
Appearance-wise, the Florida Bagworms have flat heads with black eyes and grey-brown bodies with dark stripes running down either side of their bodies. The Plaster bagworms are covered in small white spots and have ivory-colored shells, which make it easier for them to camouflage against surfaces.
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Are Bagworms Harmful to Humans?
Are Bagworms harmful to humans? In short, the answer is no. The truth is, bagworms won't hurt you if you come into contact with them. It would be almost impossible for one to be able to bite or sting you in any way. While some bagworm caterpillars can cause damage to plants and trees, they are absolutely not a threat to humans, but that doesn't mean you should welcome them into your home. Bagworms are still considered nuisance pests, and not only can they can cause significant damage to certain plants, shrubs, and trees if left unchecked, but as moths, they can ruin your clothes.
How to Prevent and Remove Plaster Bagworms Without the Use of Toxic Chemicals.
Keeping plaster bagworms at bay doesn't have to mean using toxic and potentially harmful chemicals. Instead, it can be done in safe and natural ways that are better for the environment.
By regularly setting sticky traps around the area where plaster bagworms are present, you can trap them before they become a nuisance. Of course, it’s also important to maintain your home’s cleanliness by regularly vacuuming carpets and wiping down surfaces to prevent future infestations.
Removing existing plaster bagworms involves making them reluctant to stay in your home. This means boosting ventilation, reducing humidity levels, and increasing temperatures while decreasing lighting. Additionally, these pesky creatures tend not to like strong fragrances or cedarwood chips, so products like mothballs can sometimes help. Overall, the key is to create an environment that is less attractive than before, so you don’t need any harsh chemicals!
How Do We Stop the Plaster Bagworm Infestation?
As plaster bagworm infestations can be incredibly difficult to control with traditional DIY pest management techniques, homeowners should consider enlisting the help of a local professional pest control company if they suspect an infestation on their property.
Additionally, keeping foliage trimmed back can expose any cocooned insects, which makes them more visible for removal by hand or with a vacuum cleaner before they have time to hatch into adults and further spread their population. Proper disposal of debris may also help prevent further spread since undiscovered adult cocoons laying dormant may still contain viable eggs, which will be released at maturity. Finally, an insecticide product containing spinosad or insect growth regulators (IGRs) may be used following label directions as part of the integrated pest management strategy against a plaster bagworm infestation.