With the cool weather of the fall season, most lawn and garden pests and diseases begin to dwindle away. Yet, there are a few lawn and garden pests that thrive off of the cool temperatures of the fall season.
One good point about fall lawn and garden pests is that they will not have the chance to last as long as spring and summer pests because the freezing temperatures of winter will kill them off long before they do a tremendous amount of damage.

Still, though, if these fall lawn and garden pests have been at it all summer long, they may stick around through the fall and wreak havoc on the remaining lawn and garden perennials, bulbs and trees.

Fall Armyworms

The most beautiful part about the fall season is the different colors of foliage that will begin to appear in September and October. Unfortunately, Fall Armyworms love to prey on this beautiful foliage during the fall months, as their name suggests, and can do damage very rapidly.

They usually appear in September and will stick around until the first big frost. The major problem with this fall lawn and garden pest is that they almost always feed at night, making it hard to identify the problem until you wake in the morning to leaves that have been chewed around the edges.

The upside to Fall Armyworms as a fall lawn and garden pest is that they are usually easy to spot, as they are a large tan to dark brown colored worm with a large stripe either brown or red in color on each side.
Fall Armyworms often like to make themselves present in cornfields in the early fall months and can cause major damage to the remaining corn crops. For those farmers and gardeners who are aware of Fall Armyworms, a pretreatment of pesticides will usually kill the larvae that are preparing to hatch. Unfortunately, the pretreatment needs to be established by late July or August to prevent damage in September.

Grubworms

Grubworms like the cool weather season and feed more in the spring and fall months. Fortunately as a fall lawn and garden pest they do not do as much damage as they do in the spring, but they can still be a concern for some climate zones, especially those that stay above freezing well into November.

Keep in mind that grubworms will usually survive over the winter and turn into adult beetles, repeating the entire life cycle in the spring, and this is why grubworms can be such a problem for all seasons.

Most of the time, they will hatch in the late summer and begin feeding on lawn and garden roots in the fall. This is when gardeners will notice patches of dead grass or grass that is squishy or can easily be pulled up since the roots are missing.

If at all possible, apply grubworm control in the mid to late summer, something with the active ingredient imidacloprid, which is a chloro-nicotinyl compound. This will kill the larvae before they get a chance to hatch in the late summer and will keep the life cycle from perpetuating.

Sod Webworms

Similar to the grubworms, sod webworms have a year long life cycle that means they can become fall lawn and garden pests as well as being bothersome during the spring and summer. Instead of arriving in the form of beetles, the sod webworms come from adult moths that usually begin laying eggs in the spring.

The difference is that their eggs hatch fairly quickly but the webworms are so small that their infestation may go undetected until they cocoon and reemerge as moths in the late summer to produce another generation that is more destructive. This is why you may see sod webworm problems in the fall months.

While it is helpful to use preventive sod webworm control through Microbial pesticides, the problem is that many of these pesticides will not only kill the moths of sod webworms, they may also kill butterflies and even non-pest moths.

The best method of prevention is to simply clean up leaves, grass clippings, mulch and plant debris in the fall months to keep the webworms from making webs in these places and producing more larvae.