Oak Leaf Roller

The past two weeks, I've been getting peppered with emails and a couple of phone calls about the "worms hanging from trees." Other calls have asked what are the little worms "falling from the trees." These little critters are actually not worms, but little caterpillars commonly called "oak leaf rollers," "inchworms," or "cankerworms." They spin strands of silk which can wrap entire oak trees when infestations are severe. They are most commonly found in oak trees, their preferred host, but can also infest other types of trees. And yes, they can defoliate a tree in a matter of days.

I'm already beginning to think that this year's oak leaf rollers are much worse than recent years due to the mild winter and wet year we have enjoyed. By the way, there is another caterpillar that can do lots of damage and create webs in trees at this time of the year and they are known as Tent Caterpillars or Armyworms, but the more serious problem right now are the oak leaf rollers.

Oak leaf rollers are normally at their population peak in mid April in the Houston area, but then again, what has actually been "normal" for the past several years when it comes to weather. Nevertheless, thanks to the mild winter and excessive moisture of early March, some homeowner (and definitely lots of golf courses) are seeing a massive influx of these critters. Some homeowners may not see relief until early May if they don't do any treatments right now.

Oak leaf rollers are not only capable of defoliating entire oak trees, but many homeowners cannot spend time outdoors without being bombarded by caterpillars falling out of the trees. Can I hear a collective EEEWWWW!!!!

It is important to understand that oak trees have been battling outbreaks of oak leaf rollers long before humans intervened. And in many cases, doing nothing is the best solution to the problem. A defoliated trees will almost always grow news leaves. However, weakened or stressed trees are more susceptible to severe and irreversible damage by oak leaf rollers as well as other insects and may have to be treated with pesticides. And in residential areas, where trees are valued, protection is usually desired.

There are a variety of products available to treat your oak trees. Products that contain Bacillus thuringiensis or Bt will kill only the caterpillars and spare other insects, including beneficial insects. Insecticides with the active ingredient carbaryl (Sevin, as an example) are also effective as well as any other product labeled to treat "oakworms" or "caterpillars." These are typically sprayed into the trees and kill the caterpillars that come in contact with the pesticide.

Treating the grass around the trees may kill off the surviving caterpillars and prevent them from becoming adult moths which will produce next year's oak leaf rollers. If you cannot or do not want to spray the trees yourself, a pest control company can do the work for you.