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Let's Talk Tent Caterpillars

Tent worms are species of caterpillars, they have long slender bodies up to 2” (5 cm) long with white marks on their back and hairy spines and are common in the entire state of Maryland. It’s vital to get rid of tent worms as the caterpillars can damage a whole tree, stripping it of foliage. Tent worms get their name from the large tent-like webs that they spin to protect larvae.

Tent worms have natural predators that help to control their numbers. However, hundreds of these plant-destroying crawling insects can emerge from tent-like nests in spring. The larvae are hungry and can eat their way through a tremendous amount of vegetation.

Some natural ways of eradicating tent worms (tent caterpillars) include neem oil, Bacillus thuringiensis bacterium, and introducing beneficial insects. You can prevent tent worms by removing the caterpillar egg nests in the fall.

Tent worms are the larvae of several species of moth native to North America. In the larvae stage, tent caterpillars congregate in masses on trees in spring and summer. Most species of tent worms have dark segmented bodies with white markings. Tent worms are found on deciduous trees.

Tent caterpillars are active in late spring and summer. As with most species of caterpillars, tent worms have a ravenous appetite. Although the hungry caterpillars won’t kill infested trees, they can destroy their foliage, leaving infested trees completely bare.

Tent worms are similar to fall webworms. Both species of caterpillars weave tent-like web structures for protection. However, tent worm nests tend to be in the crotch of tree branches, whereas webworms are generally on branches’ ends. Additionally, tent caterpillars destroy plants in spring and summer, and webworms are active in the fall.

The life cycle of tent caterpillars starts in a cluster of eggs that female moths lay on branches. The caterpillar egg cluster looks like a brown mass attached to a branch. There can be up to 400 eggs in one cluster.

The tent worm eggs hatch in spring and soon go to work, devouring foliage on the host tree. The young larvae are gregarious feeders and chew their way through new buds, leaves, and flowers. After hatching, the caterpillar grows and goes through five instars in six weeks. By this time, the tent worms are around 2” (5 cm) long and almost hairless.

The next stage on the tent worm life cycle is the pupa stage, where the caterpillar turns into a moth. After two weeks, the moths emerge from the cocoons, and the females lay eggs again, where the tent worm cycle begins again.

When it comes to eradicating tent worms, it’s good to know that the pesky caterpillars only have one generation a year. If you get rid of the tent worm eggs, you will have few—if any—caterpillars the following year to deal with.

Where to find tent worms

The first step of eradicating tent worms is knowing where to find the creepy crawlies. It’s vital to inspect ornamental plants, fruit trees, and shrubs in your yard. Look for thick silky tents where branches meet the main stem or tree trunk. It’s not uncommon to find many small tent worm nests on trees or bushes.

If the infestation is already large, you may notice masses of black caterpillars wriggling around the tent worm nest. You will also probably see damaged leaves where the web-spinning caterpillars have been feeding.

You can get rid of tent caterpillars in the early larval stage by removing the silky web nests. Take a stick and wind the silk webbing around it as if you were making cotton candy. Removing the caterpillar nests is just the first stage in eliminating tent worms from your yard.

Tent worm damage

Defoliation is the most significant damage that tent worms cause. If left unchecked, hundreds of tent worms can strip foliage from flowering trees, fruit trees, shrubs, or ornamental plants. Although tent worms rarely kill trees, the caterpillar damage makes plants look unsightly. Tent caterpillar damage also slows down plant growth.

Part of the reason tent worms are such destructive caterpillars is that they feed in groups. The crawling creatures leave their protective webs during the day to gorge on vegetation. The ravenous worms may also start feeding on nearby shrubs and plants, causing even more devastation.

How to get rid of tent worms

Killing tent worm eggs and larvae can help protect your garden plants from severe damage. Getting rid of tent caterpillars requires removing and destroying the nests, treating plants with a natural insecticide, and preventing tent caterpillar moths from laying more eggs.

Let’s look in more detail at ways of getting rid of tent caterpillars from trees, shrubs, and ornamental plants.

Remove tent worm webs by hand

The first step in your battle against tent caterpillars is to remove the worms by hand. The best time to catch these leaf-destroying pests is in the early morning or evening. Typically, this is when you’ll find the gorging insects in their web tents.

To kill the tent worms without chemicals, take a large stick, and wrap the silky web structure around the end. Then put the web along with the masses of caterpillars into a bucket of hot, soapy water. The hot water and dish soap will suffocate the fat tent worms.

Organic neem oil spray to kill tent worms

Use a natural neem oil spray to kill garden pests such as tent caterpillars. Make a neem oil spray by combining 2 teaspoons neem oil, 1 teaspoon liquid Castile soap, and 1 quart (1 l) of warm water. Mix the ingredients in a spray bottle and liberally spray areas where you see tent caterpillars to get rid of them.

Use the neem oil spray once a week for best results in getting rid of tent worm infestations on trees, shrubs, and ornamental plants. Neem oil works on tent worms because it contains azadirachtin—a naturally-occurring insecticidal substance. The natural pesticide interferes with larvae growth and development and prevents them from feeding. By spraying plants with neem oil, you will protect them from other nasties but not harm beneficial insects or bees.

According to research on neem oil, a solution with neem oil is effective against various larvae types. Studies have shown that applying neem oil prevents larvae from developing, poisons larvae and adults, interferes with metamorphosis, and has a repellent action.

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