LDD Moths

In the spring of 2021, there was a community-led effort to have Zimmer Air Services spray for LDD Moth in Lambton Shores. To support those efforts, Council committed to and completed: 

• Adding an LDD Moth information page to the municipal website
• Alerting all property owners by mailing out LDD Moth information
• Waiving any objection to BTK spray
• Coordinating permissions needed by other levels of government
• Putting money in the 2021 budget to control LDD Moth on municipal property

On May 31, 2021, Zimmer Air Services Inc. advised the Municipality that their 2021 Aerial Spray Program for the control of LDD Moth in Lambton Shores was complete.

What is BTK spray?

Baccillus thuringiensis subspecies kurstaki pesticide (Btk) is a bacterium found naturally in soils. It has been used worldwide as a biological pest control agent to combat a group of insects called lepidopterans (which include the LDD Moth) in forestry and agricultural settings. Btk is also approved for residential and commercial use including aerial application over residential areas.

According to Health Canada, Btk poses little threat to human health either through handling products directly or through indirect exposure such as aerial spraying.

Lambton Public Health has no public health-based objections to aerial spraying of Btk as part of a moth control plan provided that the rules of application as outlined by the Pest Control Products Act and other applicable federal or provincial legislation are strictly followed.

More information about Btk in Lambton Shores.

encouraged to monitor trees on your property.  Look for egg masses during the winter, caterpillars in spring, and moths in July and August. There are a number of actions that you can take to control LDD Moth at all stages of its life cycle.

The Ausable Bayfield Conservation Authority provides helpful information for controlling the pest throughout its lifecycle in this factsheet: ABCA Factsheet 

The Ausable Bayfield Conservation Authority provides helpful information to homeowners as an alternative (or addition to) aerial spray programs in this factsheet: ABCA factsheet

There are many local landscape and tree companies that also provide various tree health services. This includes tree climbing, pruning and removal, deep root fertilizing, as well as systemic insecticide tree injections and ground based spraying.  Although not an endorsement of any particular service the following list of companies may be considered:

• Davey Tree Expert Co. of Canada Limited – London - 1-866-243-0554
• Tri-County Tree Service – Grand Bend - 519-318-2855
• Quality Tree Service – Grand Bend - 519-238-6173
• Ontario's Choice Tree Service Inc. - Forest - 519-786-8733

LDD Moth spend the winter as partially developed larvae in eggs. The eggs hatch in the spring and the young larvae begin feeding by cutting small holes in the surface of leaves. As the larvae develop, they feed on the edge of leaves. Larvae have five pairs of blue and six pairs of red spots along their backs. Feeding is normally completed by early to mid-July.

Pupation occurs in a cocoon which can be found on a variety of surfaces including trees, rocks, houses, boats, trailers, fences, picnic tables, and firewood. In 13 to 17 days, the moths emerge. Both sexes have wings, but only the males can fly. The male moth is dark brown to beige, medium-sized, and is a very erratic flyer. The female is mostly white and has a wingspan between 60 to 70 mm. The female lays eggs in masses of 100 to 1000 on tree trunks, branches, houses, fences, etc. as well as under rocks and forest floor debris. The eggs are covered with fine brown hairs from the female’s abdomen. The egg masses will remain all winter and caterpillars will hatch in the spring, from late April to mid-May.

According to the Ausable Bayfield Conservation Authority, Oak, Aspen, Birch and Basswood are the tree species in our area that are preferred by the LDD Moth. However, depending on a variety of conditions, including high populations, the LDD Moth will eat whichever tree species is available. 

Tree damage depends on a number of factors including:

• The degree of infestation
• Past defoliations
• The tree’s vulnerability, and
• The environment.

Damage to the tree can range from light, to almost complete defoliation. Death to a tree occurs in cases where a tree has been weakened or stressed by other conditions, and defoliated repeatedly in successive years.

Many attacked trees see regrowth of leaves later in the season.

Yes. Predators include other insects like wasps, flies, beetles, ants and spiders as well as birds such as chickadees, blue jays, robins and nuthatches. Animals such as chipmunks, squirrels and raccoons will also prey on the caterpillar.

The wasp that targets the LDD Moth is a parasite of the LDD Moth egg. It is now commonly found where ever LDD Moth is and has become an important natural control of the LDD Moth.

Also, the LDD moth is susceptible to several naturally occurring diseases caused by bacteria, fungi and a virus. The virus and bacteria escalate when LDD Moth populations peak. The LDD Moth virus disease is often referred to as “wilt” because dead caterpillars hang in an inverted “V” from tree trunks or foliage.

These natural biological controls contribute the most to keeping levels within a normal range and tend to become more prevalent as the LDD Moth populations peak.

The links below provide additional information about the LDD Moth caterpillar.

• Ausable Bayfield Conservation Authority – website and fact sheet
• Ontario's Ministry of Natural Resources and Forestry
• Government of Canada
• Zimmer Air
• Invasive Species Council
• Forest of Ontario Cottagers' Association