Obliquebanded & Pandemis Leafrollers

These native insects can be found widely throughout the temperate regions of North America. They will feed and breed on many types of plants, but their preferred hosts are in the Rosacea family - specifically apple, pear and peach trees. Both of these leafrollers have two generations a year, with one generation of larvae overwintering under the bark of a host tree. Young larvae will begin to hatch in spring, just about the time trees are producing their first fruit buds. They will be fully developed within weeks of fruit development. As you can see, this portion of their life span is timed perfectly to allow the larvae to take advantage of the food supply that tender shoots and succulent fruit provide. The immature insects will then earn their name and roll up leaves to hide and pupate in. Pupation is short-lived (only 10-12 days), after which the moths will emerge to fly and mate (this is usually mid-June to early July). Once they mate, the females lay their eggs on leaves. The incubation of the eggs is as short as the pupation period - only 10-12 days. Once hatched, these larvae will crawl to their feeding site (the nearest healthy tree, especially those bursting with fruit). They can also spin silk strands and set sail on the wind. The second generation of adult flight is usually mid to late August.

Controlling Obliquebanded & Pandemis Leafrollers: Controlling leafrollers takes some patience and works best when several of the life stages are treated.

  1. Scout for larvae early in the season and act quickly if you find any. Bacillus thurengiensis, spinosad or azadirachtin sprays can be used on the larvae with good results when diligently and thoroughly applied. Using a high-pressure power or forceful hose-end sprayer can aid in getting the spray up into the canopy and into hiding places that the larvae prefer.
  2. When adults take flight, traps and lures can be utilized to monitor the population. This monitoring can give you valuable information on your insect population. Because these lures will draw in the males, this sort of trapping can also reduce the population number by reducing the number of adults out there mating.
  3. Pheromone attractants (mating disruptors) can be deployed when adults are actively flying in search of mates. These pheromones interrupt and confuse the communication between the sexes, which keeps them from successfully mating.
  4. During the winter, when dormant trees may be harboring overwintering larvae, horticultural oils can be applied to the tree. These suffocants will only kill those larvae that they come into contact with, so thorough coverage of all tree/leaf surfaces is essential. If leafroller larvae is well placed under the bark, oils may not be effective. Close scrutiny come spring is recommended for any treated trees.