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Recycle A to Z

alternatives to pesticides - bugs/pests - leaf rollers

                            leaf rollers
                    Actual size: Moth 3/4”  Larva up to 1

There are many types of leaf rollers that infest many different plants, including apple, willow and plum trees, blueberries, photinia and laurel.  The larval stage is a caterpillar that folds the leaf and webs it, then feeds inside it.

Physical control
Remove - Remove them or the leaves they are in from the plant. Do not put them in your compost bin unless you bury the leaves in the deepest, hottest part. It is better to put them in a sealed paper bag and place it in the garbage.

Biological control
Wasps - Encourage native parasitic wasps such as Trichogramma.
Bacillus Thuringiensis (Bt)- Bt the bacterium that paralyzes the digestive system of the pest, may be used according to label directions. However it is difficult to deliver to the areas where the larvae are feeding. The rolled leaves provide good protection.  Bt is a bacteria used to control certain pest larvae, primarily caterpillars. Bt is not toxic to humans or other mammals but will kill butterfly (“friendly”) caterpillars as well as the problem ones. The bacterium kills larvae by interfering with digestion. Bt lasts on leaf surfaces five to seven days and must be ingested to be effective. There are many strains of Bt commercially available now, including strains for controlling mosquito and beetle larvae.

Least-toxic chemical control
Pyrethrum - Dust or spray with pyrethrum for severe infestations only. Apply in two applications, 30 minutes apart. The first drives the caterpillars from hiding, the second kills them.  Pyrethrum is an effective, short-lived, naturally derived insecticide made from chrysanthemum flowers. It is toxic to all insects, including beneficial ones, and moderately toxic to birds and mammals. It should be the last resort for ornamentals and is not recommended on food crops. Avoid using formulations that contain piperonyl butoxide, which is currently being evaluated for its carcinogenicity.  Pyrethrins are the individual chemicals found in pyrethrum. Pyrethroids are a new array of synthetic chemicals, such as cyfluthrin and cypermethrin. They resist breakdown, thus negating their major environmental advantage. With the three names being so similar, they can easily be confused. Pyrethrum is the least hazardous.
Rotenone - Dust or spray with rotenone for severe infestations only. Apply in two applications, 30 minutes apart. The first drives the caterpillars from hiding, the second kills them.  Rotenone is a tropical plant-derived insecticide that is harmful to insects, fish, birds and mammals. Read labels to see if the product is mixed with other pesticides. Check the label to see if the pest problem and the plant you want to protect are listed. It is toxic and should be handled with care.  Follow label instructions exactly.


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