Tent caterpillars are a very active pest from year to year. They have ferocious appetites and will eat most any plant they find. Their nests are unsightly, their eating will injure plants and they readily migrate into most any structure making a mess along the way. This article will detail all you need to know about tent caterpillars and then explain how and what to use for controlling local infestations and nests on your property.
TENT CATERPILLAR BIOLOGY
Tent caterpillars are 2 to 2.5 inches long. They are generally dark – mostly black – with a few long, bright colored stripes which run down their back. Blue dots are commonly prevalent, along with other colors on their body. These lines may be brown or yellow.
Tent caterpillars will hatch from eggs in early spring. Though barely noticeable during this young stage, they will become active as local plant life starts to grow its spring foliage. It is this foliage the caterpillar larva need. They will eat what they find and if the host tree or shrub on which they originate does not provide adequate food, they will migrate to other nearby local plants.
For the next two months, the larva will feed during the day growing bigger and bigger. At night they will return to their host tree and start to spin a constantly growing “tent” in order to accommodate their ever increasing size. This tent will become more and more apparent as spring turns to summer and then in late summer, their nests can get HUGE.
Generally unsightly, these tents are white and silky looking usually appearing where limbs of the host tree grow in two separate directions. This forked location provides a good strong foundation on which their nest can support the ever increasing weight of the local colony. These colonies will start out with several hundred caterpillars and “tents” can be as small as a soccer ball or as large as a small car!
By the end of August, feeding larva will have reached maturity and will instinctively want to leave their nests. Tents will be vacated and caterpillars will be seen migrating in all directions with no specific destination. They will be seeking a place to hide and pupate but they aren’t quite sure where this place will be.
During their migration, they will commonly crawl on homes. They will be seen on the sides of houses and some will end up inside if proper treatments are not done to keep them out.
Once a comfortable location is found where they feel safe and protected, they will spin a cocoon and undergo metamorphosis. In another 2-4 weeks they will emerge as adults, find a mate and reproduce.
Females (adult moths) will find a suitable host plant on which to lay eggs and once found, will leave 200-300 eggs on a branch held together with a sticky substance which is part of the egg laying process. Adults will then die in late summer and eggs will rest till next spring when larva will hatch and start the cycle all over again.
TENT CATERPILLAR PLANT DAMAGE
Tent caterpillars can do a lot of damage when they feed. Though their feeding only defoliates host plants and rarely causes immediate problems, plants which loose a lot of leaves will suffer later in the growing season. Besides looking odd with no leaves, they won’t be able to perform normal photosynthesis, they will have to spend a lot of time and energy growing new leaves to replace those which were lost and because of this, will be a lot more vulnerable to other problems like disease and parasites. In general, its not good to let tent caterpillars have their way when they identify a plant on which to feed.
Furthermore, caterpillar droppings will be found underneath host plants and will make a mess on cars, homes, lawn furniture, etc. They eat a lot and consequently, they defecate a lot. These droppings will be found under any host plant and can become quite an issue if a large local population is feeding.
Rarely will the droppings cause damage but do not let them lay on cars. Their droppings are acidic and will “eat” through most any car finish causing rot. Be sure to clean up their mess to avoid such staining or burning.
HOW BIG WILL A TENT CATERPILLAR NEST BECOME?
As each caterpillar grows in size, their colony will make their “tent” larger. Though caterpillars start each season small and barely noticeable, they will grow to be over 2 inches in length and the nest “tent” will have to made bigger to accommodate each individual’s larger size.
Since several hundred caterpillars may commonly live in any one tent, these nests will become significant in size over the course of a summer. Don’t be surprised to find nests the size of a basketball or larger. In general, such additions should not be welcomed in any tree or bush and if left untreated, expect more to be around the following year. Trees in which nesting is successful will tend to attract more from year to year as previous generations will instinctively know a good host plant. By allowing any nest to reside undisturbed on your plants you are basically inviting more to come around year after year.
And if the damage, droppings, or unsightliness of their nests isn’t enough to make these insects a bona fide nuisance, their annual migration surely will. This migration will come during the end of their larval stage.
Once larvae have had enough to eat, they will start to leave the main nest in search of a good location where they can undergo metamorphosis. This last stage is a kind of semi sleeping stage where they won’t be moving or feeding. They like to choose secure and discreet locations for this change and seem to like man made structures just as much as any tree.
For this reason its not uncommon for any one house to have hundreds of these pupating tent caterpillars if left untreated. The migrating larva will be out in great numbers during this time traveling in all directions from the main nest and if they encounter a home or other structure, chances are they will try to make it their home for the next month. Since there are so many small cracks and crevices for them to enter a house, expect to find some inside living areas. In fact many homes will actually get invaded each year if they are located in the migration path of tent caterpillars. During this time their house can be covered with larva which are simply looking for a good place to complete their life’s cycle.
ORGANIC TENT CATERPILLAR TREATMENTS
Anyone growing an organic garden might want something that’s labeled and certified for use on your organic fruit and vegetable crops. There are a few organic products approved and certified for caterpillars but we have found MULTI PURPOSE INSECT KILLER to perform the best.
Mix 5 oz per gallon of water and apply the mixture over no more than 800 sq/ft of foliage. Retreat as needed but we have found if you can “poke” some holes in the tents, the Multipurpose mixture sprayed directly into the their tents will yield an instant kill. Be sure to treat as many tents you can find on and around your property. Once the soon to pupate caterpillars start migrating, they’ll end up in your garden if its not properly protected.
BEST TENT CATERPILLAR SPRAY
The strongest spray available for killing tent caterpillars immediately is our MAXXTHOR EC. This concentrate should not be used on food crops but its excellent for spraying all trees, shrubs and the homes siding if you’re seeing foraging or migrating caterpillars.
Maxxthor has a fast acting ingredient that will both take out moving caterpillars as well as repel them off the treated surfaces.
When the late summer/fall migrations being, you might have to spray once a week to knock them out unless you know where they are nesting.
If you can reach their tents, use a long pole to poke holes in them and then drench the tents directly for a fast kill of all inside.
For open turf, the sides of trees and plants, add 1/2 oz of Maxxthor to a gallon of water and use this to spray over 1000 sq/ft of area.
The preferred way to apply Maxxthor is using our 6 GALLON HOSE END sprayer. With this sprayer, you’ll add 3 oz of the Maxxthor and then fill it with water. Hook it to your garden hose and apply the entire mixture over up to 6,000 sq/ft of turf and plant foliage surface area.
Since caterpillars are “hairy”, adding some SPREADER STICKER to your tank mix will really help. This additive will allow the concentrate to better “coat” the target plant and caterpillars when spraying them directly.
When spraying plants, its usually hard to get good coverage because leaves have undersides that will mostly avoid direct spray. Spreader Sticker will help get coverage in these areas by dispersing the spray once it lands on targeted treatment sites. And it will enhance the immediate impact the Maxxthor has on targeted caterpillars.
Add equal amounts of the Sticker to your tank mix as you add the Maxxthor. So if you’re adding 3 oz of Maxxthor to our sprayer, add 3 oz of the Sticker too and then the water.
HOW TO TREAT TENT CATERPILLAR NESTS DIRECTLY
If you have a bunch of nests you want to treat directly, there are two options. The MAXXTHOR EC with SPREADER STICKER listed above will work great assuming you can poke some holes in the tent. This can be tricky since most nests will be high up in the tree and the webbing can be quite thick but well worth the time and effort.
To treat active tents, wait till evening. This will insure all caterpillars have returned and will be laying inside.
Next, prepare the spray and be sure the sprayer you have will reach high enough to soak the nest.
Using a stick or pole, poke 3-4 holes in their tent. Holes should be large enough to allow the treatment to penetrate but not too large that all caterpillars fall out.
Once access holes are made, spray the solution you have prepared on the nest. Soak it to the point of runoff thus insuring the ones present will be killed and that there will be a lasting residual to get any that may be away.
HOW TO GET RID OF TENT CATERPILLARS ON THE HOUSE
If your home is being penetrated by the migrating adult tent caterpillars, there are two products which will both keep them from entering and kill them if they try.
SPRAY THE HOMES SIDING WITH MAXXTHOR
First, spray the entire outside of the home with the MAXXTHOR listed above.
Be sure to spray from the gutters down to the foundation.
If the house already has caterpillars up in the eaves and under soffits, spray with the Spreader Sticker added. Maxxthor is super irritating to caterpillars and will kill off those present as well as leave a good residual to keep them away.
If they’re already in the home, use FS MP AEROSOL. to all routes of entry like windows, doors, etc. Its great for penetrating all the cracks and crevices these caterpillars want to use and it comes with a handy tube injector. It too can be applied along baseboards, around window frames and up high by crown molding.
Tent caterpillars will remain active for a few days inside the home so its important to get a good treatment down as soon as possible. If not done early enough, expect to see a lot of adult moths hatching out of pupa cocoons in 1-2 months following the initial invasion.
EQUIPMENT NEEDED FOR TENT CATERPILLAR TREATMENTS
When spraying for tent caterpillars, any PUMP SPRAYER will do the job. Our standard sprayer can reach up around 15 feet and is fine for low applications.
Another option is a good HOSE END SPRAYER. These will reach as far as your garden hose can spray.
Tent caterpillars are mostly considered harmless pests. However, their chewing and eating can cause damage and stress to a lot of trees and plants once they start their spring feeding. Keep them under control in the yard with any of the concentrates listed above. With any luck, this will keep them from getting inside. But once on the home, use Maxxthor and FS MP Aerosol to knock out the invasion. Treat early in the season to keep tent caterpillar numbers in check; kill off as many as possible once the season is in full bloom otherwise you will have that many more to deal with next year.
Give us a call if you need further help. Our toll free is 1-800-877-7290 and we’re open Monday through Thursday, 9:00 AM to 4:00 PM. On Friday, 9:00 AM to 4:00 PM and on Saturday, 9:00 AM to 2:00 PM (Eastern Standard Time).
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