Control of Tent Caterpillars in Ornamental Trees

Although they're cute and fuzzy, caterpillars can do extensive damage to trees.

Large, towering trees can be brought down by tiny beetles, moths and their larval caterpillars. These animals devour wood quickly and can grow to be a dangerous infestation unless they are controlled.

The Facts--Caterpillars

Caterpillars are actually the larvae of wood-boring beetles and moths. These insects lay their eggs in trees that provide food for their young once they've hatched. Caterpillars attack both soft and hard wood, and can move from tree to tree and onto wooden structures in the area.

Damage and Symptoms

Symptoms of caterpillar damage can range from minor to overwhelming. The initial signs of caterpillars hatching and eating wood include the tracks of the worms: worm tracks and tunnels through the the wood. Serious infestations can result in dying vegetation and large sections of dead wood.

Pesticides

To kill a population of caterpillars and their parent beetles and moths, the quickest way is through the use of pesticides. Pesticides are sprayed over the trees to kill the insects on contact or poison the wood to kill caterpillars that way. These pesticides do not harm the trees themselves, but make the wood toxic when eaten.

Organic Controls

For people who do not want to use highly toxic pesticides in their yards, there are a couple of all-natural options. Neem oil is natural, nontoxic and highly effective against insects. Beneficial insects like ladybugs and lacewing moths eat caterpillars in their larval stages. Attracting lizards and birds to the area to eat caterpillars and beetles is another option. Birds can be attracted by setting up bird feeders, while lizards can be purchased and then freed in the area.

Considerations

Wood that has been damaged by beetles and caterpillars cannot actually be repaired, and chances of regrowth in those areas are not good. It is best if the damaged areas are pruned away, to save the tree from attempting to heal them and to prevent reinfestation. Beetles are most likely to attack wood that is already weak and damaged.

References

• NovaGaurd: Wood Boring Beetles
• UC IPM Online: Wood-Boring Beetles in Homes
• Texas A&M: Texas Agricultural Extension Service: Wood-Boring Insects of Trees and Shrubs