Caterpillars in Your House? These 10 Tips Will Keep Them Out

Caterpillars come in all colors and sizes – but if there’s one thing we can all agree on, it’s that they’re unsightly. You won’t believe how many times I got a morning surprise from seeing these buggers staring at me while hanging out on the wall of my house — yeah, inside my house!

To keep caterpillars out of your house, you can use the following steps:

• Keep moths from entering your house.
• Get rid of moths and moth eggs from inside your house.
• Move the caterpillars out of your home. 
• Concoct soap-based homemade pesticide. 
• Make some homemade chili spray. 
• Use Bacillus thuringiensis. 
• Use pyrethrum. 
• Buy a pesticide from the store. 
• Create an insect barrier around your plants. 
• Keep as clean as possible.

Caterpillars can be difficult to deal with. If you’re dealing with an infestation, the following article will tell you everything you need to know to get rid of these pests and reclaim your home.

Caterpillars as Pests: a Brief Overview

These insects are usually harmless, except, of course, for the typical irritation that comes with a burning or stinging sensation you’ll get from touching a caterpillar.

This irritation is called caterpillar dermatitis, and there have been at least 16 species of caterpillar that can cause severe effects. Although more species can cause mild irritation, people may have opted to leave it unreported due to its insignificant rash and itch. Now I’m not a doctor here, so that’s the most I’ll say regarding that topic.

The biggest concern that you might have with a caterpillar infestation in your house is that they feed on foliage like there’s no tomorrow. Failure to control it can lead to the destruction of plants, both indoor and outdoor.

Over time, these caterpillars will stop eating, then form cocoons and hang unto a branch until they turn into butterflies or moths. That’s when they become an integral part of pollination. So, although there are some tips that I’ll share with you on how to get rid of these insects permanently, it would be best if you think of it as your last resort.

I was fortunate enough to have some experience in dealing with these infestations, but I figured that if I’m getting these “jumpy moments,” it’s most likely that some people do too.

How Do Caterpillars Get Into Your Home?

Before we dive into the part where you manage an infestation and keep the caterpillars out of your house, let’s answer something a bit more important — how do caterpillars get into your home?

Maybe you have plants in your home (I do), or maybe you’re just messy or inviting to these critters.

Caterpillars don’t move around as much as people think. They usually appear in the fall, but sometimes, you can find them at other times, especially when the weather is warm.

Caterpillars only move to a place where there’s a constant supply of food that they can forage on until they pupate. So the bad news is that caterpillars in your house were, most likely, born there.

If there are moths and butterflies around your house, they’ll always look for ways to populate and find places where they can lay their eggs. So before you deal with a caterpillar infestation, it would be best to get to the root of the problem: moths and butterflies.

Moths are usually the ones laying eggs inside houses because they don’t eat at all. If you see them clustering around, they’re laying eggs, and they do it in places near a food source. They need to do this because caterpillars will die if they have to move too far to get to their food.

If you have caterpillar infestation inside your house and you want to keep them out, you have to get rid of the moths first.

How to Keep Caterpillars Out

Caterpillars are rarely harmful to humans, but they carry destructive wrath on plants.

Keeping caterpillars out of your house only needs one thing — get rid of the source. If you’re here, you’re probably already dealing with caterpillar infestation.

Tip #1 – Keep Moths From Entering Your House

The best and most cost-effective way of keeping the caterpillars out is to make your house less attractive for moths to lay their eggs. It may require constant, general clean up every month, but it’s a lot better than dealing with caterpillar infestation.

So for the first tip, here are a few things that you can do to prevent moths from laying their eggs inside your house:

• Wash and dry all of your clothing — even the ones that you don’t wear. If you have several clothes that you’re not using regularly or aren’t planning on wearing for a long time, it would be best if you can keep these in sealed plastic bags or boxes. These containers will prevent long-term infestation, making it easier for you to keep the caterpillars out of your house.
• Vacuum and clean your closet, wardrobe, or whatever you use to store your clothing — It’ll be easier to deal with the infestation if you can keep your dirty clothes in a sealed hamper. Moths are attracted to sweat and moist, so keep your clothes safely stored until you wash them to prevent moths from laying their eggs.
• Clean Your Pantry — Moths lay eggs close to the food source to make it easier for caterpillars to have enough to forage on until they pupate. In your house, the pantry is the safest place with the most-accessible food sources — fruits, grains, and cereals. Keep it clean and remove crumbs regularly. Don’t leave your food in the open and keep your fruits refrigerated.

There’s no reason for you to panic when you see a caterpillar in your house. They’re just a cause of other more pressing concerns. Depriving moths of what they need will force them to move elsewhere to lay their eggs. If you see a caterpillar in your house, deal with the source directly, and prevent them from feasting on houseplants.

Tip #2 – Get Rid of Moths Inside of Your House

Managing the infestation will be much easier if you’ve identified the source. Once you’ve ensured that moths can’t lay their eggs inside your house, it’s time to get down to business — managing the infestation.

Now, it’s time to manually get rid of the caterpillars in your house, starting with the use of a broom to remove caterpillars off the walls.

Caterpillars could be in one of three locations: where they hatched, on the way towards their food, or enjoying their time unleashing their wrath on your foliage. You’ll have to brush them off with a broom daily to prevent caterpillars from leaving a trail that could potentially stain your house.

When handling insects and especially caterpillars because they can cause irritation, it would be best to use tweezers or rubber gloves for your “search and destroy” operation.

Unless you’re an expert, never hold a caterpillar with your bare hands. With the number of species of caterpillars that are known to cause caterpillar dermatitis, it’s most likely that the one in your house can cause rash and itch.

After your mission, the last thing that you need to do to get rid of caterpillars in your house is to sweep away cocoons. Check your plants or places close to their food source, and make sure that you collect everything.

Now, if you can help it, go ahead and place the caterpillars outside far away from your home. This will ensure they can remain a vital part of the ecosystem.

Tip #3 – Relocate the Caterpillars!

Aside from caterpillar dermatitis, there’s almost no risk or any form of aggression from caterpillars. So instead of getting rid of the infestation permanently, you may want to relocate the caterpillar outside your house.

I believe that this is the best course of action, given the role of moths and butterflies in pollination, and possibly their contribution to your yard’s ecosystem. If they’re inside your house, there are no plants to pollinate, and their contribution to your yard’s ecosystem goes down to zero.

After collecting the caterpillars with a tweezer — assuming that you didn’t squeeze too hard — take them out on your yard, then dump them onto a tree branch or leaves. It’ll provide them with enough food until they pupate and start contributing to the natural growth of plants and trees.

Tip #4 – Use a Homemade Soap Insecticide

Soap insecticide is the most cost-effective way to get rid of caterpillars in your house. Why? Because you only need soap and water.

It’s the safest mixture that you can use, given that you’re using plant-based and biodegradable soap. It won’t harm plants and animals but is highly potent against caterpillars. The catch is, you’ll have to use it daily until you rid your house of the infestation.

One option is to mix soap with water in a small container with sprayer, then spray it on the caterpillars inside your house. This mixture destroys the skin of the caterpillar, but, unlike other formulas for caterpillars, you’ll have to spray soap insecticide directly on them for it to be effective.

Check the underleaf of your houseplant daily until you get rid of all the caterpillars. This technique might take days, but it’s the safest and cheapest way to get rid of caterpillars.

Since you have to spray the mixture directly on the caterpillars, unless its a bad infestation, the best recommendation is to take them outside and do as little harm as possible.

Tip #5 – Make a Homemade Chili Spray

Homemade caterpillar repellents are excellent for infestation, because you know its composition, and you’re sure that there are no harmful chemicals. Chili spray is an upgrade from soap insecticide.

One study found that chili powder mixed with water helped to yield higher plant crops vs other botanicals ¹. If you’re interested in this method, you can find a very simple guide to a similar concoction here. If caterpillars are around your plants, the plants will show a reaction to this mixture. This mixture works the same as the soap insecticide; it only works faster in destroying their skin and stopping them from foraging on plants.

If these buggers are inside your house, then take them outside if you have the possibility before spraying them. Likely though, you may have a bad infenstation.

Tip #6 – Use Bacillus thuringiensis var. kurstaki

Bacillus thuringiensis var kurstaki or BTk is the preferred choice for insect infestation, mainly against lepidopterans—an order of insects that includes moths, butterflies, and 112,000 other species. Farmers and agriculture experts prefer BTk for insect control because it doesn’t cause harm to birds, bees, fish, and mammals, making it the safest and most eco-friendly option for exterminating lepidopterans.

BTk, in layman’s terms, is a bacteria that occurs from decaying materials in the soil. It targets the digestive system of caterpillars, making it highly effective in managing their infestation. But you have to apply BTk in plants because caterpillars need to ingest it to work.

As the USDA Forest Service report states, BTk is an extremely effective solution that only affects lepidopterans, making it safe for household use. BTk-treated leaves will take 3-5 days to take effect on caterpillars. Furthermore, research performed by the Environmental Protection Agency concluded that there generally aren’t any significant health hazards of BTk with normal and practical use ².

Furthermore, the Michigan State University touts BTk as a management option for gypsey moth but only if the infestation is severe.

BTk is a commercially available pesticide, so your local home improvement store may have it on their shelves. Simply mix it in water, then spray ample amounts on the leaves of your plants. 

Tip #7 – Use Pyrethrum

Pyrethrum is a natural insecticide from chrysanthemums, and it contains six esters; jasmolin I & II, cinerin I & II, and pyrethrin I & II. We don’t have to get into the details on how they manufacture this insecticide, but it’s organic and commonly used as household aerosols and garden insecticides for pest control.

Pyrethrum is listed as possibly safe for humans with normal use by WebMD. Pyrethrum does some work for most insects, including caterpillars, but you need to spray it on the infested plant regularly.

Exposure to sunlight degrades its effects; that’s why BTk is more advisable if you’re planning to use insecticides for caterpillar infestation that takes place on plants.

If you happen to find a product that contains “pyrethroids,” it’s a similar product with a similar effect. The only difference is that pyrethroids are synthetic versions of pyrethrum.

Tip #8 – Use a Commercial Garden Pesticide or Bring in a Pro

Using a pesticide is an extreme measure, and you should only resort to this method with careful consideration and utmost caution. Most commercially-available pesticides contain high-levels of toxicity for caterpillars, animals, and humans — even those that specifically target caterpillars.

It can also cause poisoning if you are cultivating houseplants that you use for personal medication and relief. That’s why there’s only one acceptable instance where you should use commercially-available pesticides — extreme infestation.

Tip #9 – Build an Insect Barrier

There’s one apparent reason why you’re dealing with a caterpillar infestation — your houseplants. These ornamental plants are the only reason why moths lay eggs in your house, but I understand that it adds to the aesthetics and creates a beautiful vibe. So let’s keep it that way.

You can use an insect barrier for your plants to prevent caterpillars from foraging on its leaves and make your houseplant inaccessible for moths and butterflies when laying their eggs. Even if moths lay their eggs, caterpillars will die off if they can’t find enough food to support their growth.

Since these are houseplants that you’re taking care of, you won’t need pollination for it. Cover your houseplants with a transparent fabric or fine wire mesh that is small enough to prevent insects from passing through.

Tip #10 – Just Keep as Clean as Possible

For any critters and creatures, not just caterpillars, it’s vitally important just to stay as clean as you possible can both inside and outside of your home.

While it may come at the cost of how beautiful your property looks, you’ll be less likely to have wildlife invite themselves into your home, and that’s a plus.

So, About Those Caterpillars…

You probably don’t want caterpillars in your home, and that’s OK. Although these insects aren’t aggressive by nature, they deliver varying doses of irritants that could affect you and ruin your plants in the process.

It doesn’t mean, however, that exterminating them is your only option. I’d recommend that you relocate caterpillars outside your house, then keep everything organized and less ideal for moths to lay their eggs. Dealing with caterpillar infestation doesn’t have to be expensive, and you won’t need professional service unless the infestation is really out of your control. If it ever feels like you don’t have a grip on things, go ahead and PLEASE do yourself a favor and hire a local professional.

References

Siddiqua, T. A., Miah, M. R. U., Amin, M. R., & Yesmin, K. (2016). Use of Botanicals as Environmentally Safe Management for Cotton Jassid. Journal of Environmental Science and Natural Resources, 9(2), 131-134.

Wagner, D. L. (2010). Caterpillars of Eastern North America. Princeton University Press.

Feeny, P. (1970). Seasonal changes in oak leaf tannins and nutrients as a cause of spring feeding by winter moth caterpillars. Ecology, 51(4), 565-581.

Scriber, J. M., & Feeny, P. (1979). Growth of herbivorous caterpillars in relation to feeding specialization and to the growth form of their food plants. Ecology, 60(4), 829-850.