March Pest of the Month OAK LEAF ROLLERS

For the past couple of years, oak leaf rollers were a major problem in San Antoino. Oak leaf rollers
are green colored caterpillars that hang from the branches of oak trees on single silk strands. They aren't necessarily harmful to trees, but they can stain driveways and make it unbearable to spend time outdoors during spring.

The best way to control oak leaf rollers is to treat the trees before they become a problem. Fortunately, the most effective control methods are organic. The best time to treat is late march, early April. Once the oak leaf rollers reach their peak, it may be too late to effectively control them.

Photo by Teresa Gold

Bacillus thuringiensis (Bt) is an organic product specific to caterpillars. Apply Bt late afternoon/dusk because the product degrades in the sunlight rapidly. Spinosad is another organic product that is much more expensive, but has many more pros. It does not degrade in the sunlight and can be applied at any time. It also provides fairly good control when applied later in the infestation.

A non-organic product to use is carbaryl. It must also be applied late in the day because it degrades in the sunlight.

Spray all throughout the canopy of the oak trees as high up as you can reach, spraying the ground directly around tree may also kill caterpillars that have dropped or are over-wintering in the soil.

Remember, timing is the key to controlling oak leaf rollers. Spray at the end of this month for maximum control and enjoy your spring!

For more information contact IPM Program Specialist and Entomologist, Molly Keck at 210-467-6575 or email at mekeck@ag.tamu.edu