Moths

To most homeowners moths are not seen as a pest. Some people may get frightening by their fluttering around, but they certainly can’t harm humans. Indeed some species can be very beautiful, but are not often seen as they are nocturnal.

However, the same cannot be said for their larval stage, the caterpillar. Caterpillars feed on plant material and they can have very voracious appetites. Whereas one or two caterpillars may not be an issue, when they occur in large numbers they can cause significant damage.

Some species, in many parts of the world, can be significant agricultural pests, such as the corn borers, bollworms and codling moths. However, for homeowners, the pest species fall into three categories:

• Fabric or clothes moths – their caterpillars eat various fabrics and clothes
• Pantry moths – their caterpillars eat a wide range of dried foods
• Lawn moths – their caterpillars eat grass

Many of the pest species are nocturnal and will hide during the day, making them difficult to locate for identification. However, once found they should be relatively easy to identify by comparing to photos.

However, it is more normal for homeowners to start the identification with noticing they have a problem – holes in their clothes, strange webbing in their flour, a decimated lawn. Once the damage is identified, it is often still necessary to dig around a bit before the culprit is found, the caterpillar. Identifying the species from the caterpillar is a but more tricky, but in reality if you’ve found a caterpillar in the area where there’s damage, you can be pretty sure what it is!

The images of the three most common pest species found around the home (above) should certainly help with identification.

Some people will also notice case moths in the garden, but these are rarely significant pests. A more likely problem for vegetable growers is the cluster caterpillar, which can be a significant problem in a wide range of crops.

Moths go through a complete metamorphosis (change in body shape) as they develop. The caterpillars hatch from the egg, which goes through several stages (moulting its skin each time) as it grows. When it is ready to turn into an adult, it crawls to a safe place and builds a cocoon or pupa. Inside the pupa it develops into the adult, emerging as a moth.

The time taken to complete the life-cycle depends on the species, the available food and the temperature (warmer temperatures speed up the development). For example a sod webworm (lawn pest) typically completes its life-cycle in around 6 weeks, whereas clothes moths take 2-3 months on average.

Individual adults are relatively easy to kill with a fly spray. However, they do have a hairy body so a water-based aerosol will provide the best performance.

However, if you have an infestation, generally that will be pantry, clothes or lawn moth, it is probably best to call a professional pest manager. They will be able to identify the species, the source of the infestation and apply an appropriate treatments.

Inspection and identification is the first step in the control process. And in the case of clothes and pantry moths it is important to find all infested containers of food or clothes.

The second stage is to throw out or treat infested items. This normally means heating or freezing items (following by washing for clothes).

The final stage is to carry out a treatment of infested areas, cupboards, drawers and lawns (in the case of lawn moths).

The treatment targets the damaging caterpillar stage. However, once the infestation is eliminated, for clothes and pantry moths it may be a good idea to use some emanation devices to repel / kill any incoming adults. Another alternative is to use sticky traps with pheromones, which are designed to trap any moths in the area. These can be particularly useful to monitoring for their presence, giving you an early indication of a potential problem.

For clothes and pantry moths there are a number of actions you can take to prevent an infestation.

For more information on the key pest species, their treatment and prevention. Click on the images above.