Garden....... Foe!!!! Wait... AND Friend!!! Wait... but why?

So like many other times we've discussed moth's and their larvae, we generally list them as both garden friends and foes. Here is a quick reminder why:

Although the larvae of moths (frequently called worms or caterpillars) are generally destructive to food crops, the adult moths are beneficial nocturnal pollinators. We always want to support our pollinators and beneficial insects. But, these caterpillars can be super destructive to plant foliage. Plus they host on numerous vegetable crops. What should we do?

First let's learn about the moth and caterpillar. At the end I will discuss management methods. Or you can skip there now if you want.

Saltmarsh Moths have a wide range from Central America all the way to Canada. Some people call them woolly bear moths because of the numerous hairs on the mature instars. But, Woollybear Caterpillars is a name generally saved for caterpillars of the Isabella Tiger Moth and look very different than caterpillars of the Saltmarsh Moth.

Adult moths have a 3-5 cm wingspan which makes them easy to notice. They do not emerge until night. They are mostly white but males do have a yellow-orange hind wing. Both sets of wings will have small black spots scattered throughout. The body will also have a yellow-orange color in addition to white. Female moths can lay around 1,200 eggs in a single cluster.

Eggs hatch in about 4 days. They are very small and spherical in shape.

Just after hatching, these small caterpillars are very hungry hungry caterpillars. They begin feeding on the closest foliage to where they hatched. While they can cause major damage, they typically do not eat through an entire leaf. As they progress through different stages, or instars, they begin changing colors. They can become brown, yellow, white, and have spots. Around the 4th-5th instar is when they will become darker in color and numerous hairs begin to grow.

As the caterpillars become more mature, they also become more solitary. This is not typical for many caterpillar species. They will leave other caterpillars in search of new food, probably to reduce competition. On large farms they have been observed leaving the borders where they began feasting on weeds in search of food crops. It is believed that this may be because the bordering weeds are not typically irrigated as well.

Another characteristic of the saltmarsh caterpillar is that it has the ability to drop from vegetation and spin a silk that allows it to be carried by the wind. Basically using the silk as a parachute to go for a ride in search of new food.

After around 20 days, mature caterpillars will begin to search for a suitable spot to pupate. This occurs in the top layer of soil. They prefer to find an area that has leaves or other debris. They spin a thin cocoon that is interwoven with their hairs. After 12-14 days they emerge as adult moths.

Managing this caterpillars is relatively simple. As always, we begin with the least "aggressive" method and work our way up to the chemicals.

1. Let the other insects do their jobs. There are many other predator insects and critters that will take care of these caterpillars for you. If you have a healthy ecosystem in your garden/landscape, these beneficial predators will show up pretty quick too! Some of the predators include:

   Tachinid Flies

   Parasitoid Wasps

   Assassin Bugs

   Birds

   Lizards

   Other opportunistic bugs and animals

   
   

2. Hand Removal is another technique to use especially when finding only a small amount of caterpillars. We encourage you to relocate the caterpillars to broadleaf weeds so they can still munch and become moths. You save your prized food crops and allow the caterpillars to still thrive. In our small experience with these caterpillars, we have not found them to sting or bite. There are some reports of people having skin sensitivity to the hairs. If you are concerned, wear a thick pair of gardening gloves.

3. Insecticidal use is an option. We recommend staying as organic as possible with sprays like Bt spray. Bacillus Thuringiensis is a liquid bacteria that targets moth and butterfly larvae but will not harm other insects. That includes the adult moths and adult butterflies. It can be found in any gardening store or online.