Why Different Insects and Spiders Increase in the Fall
As the days grow shorter and temperatures begin to drop, many homeowners notice an increase in insect and spider activity. Understanding why these pests become more prevalent in the fall can help you prepare your home and yard. In this blog, we’ll explore five common insects and two types of spiders that ramp up their activity during the fall season.
The Reasons for Increased Fall Insect Activity
1. Seeking Shelter
As temperatures fall, many insects look for warm environments to survive the winter months. Homes, garages, and sheds provide ideal shelter from the cold, prompting a surge in activity as these insects look for entry points. Cracks in windows, doors, and walls become pathways for these pests. This behavior is particularly noticeable in the fall when the temperature drops significantly, leading to an influx of various species into human habitats. [University of Illinois Extension – Fall Insects](https://web.extension.illinois.edu/pests/fallinsects.cfm)
2. Food Sources
With the onset of colder weather, food availability shifts. Many insects and spiders rely on specific food sources that become scarce as plants die back and seeds are harvested. As a result, pests often move indoors in search of sustenance. For example, ants are driven to invade kitchens and pantries, while other insects, like ladybugs and boxelder bugs, seek out the warmth of human dwellings where they can find sustenance or wait out the cold months. [Penn State Extension – Fall Pest Management](https://extension.psu.edu/fall-pests)
3. Reproductive Cycles
For some insects, fall marks the last chance to reproduce before winter. This drives many species to be more active as they lay eggs or seek mates. Female insects often seek sheltered environments to lay their eggs, ensuring that their young will emerge in the spring when conditions are more favorable. This behavior increases the likelihood of encounters with humans as these insects search for optimal nesting sites. [North Carolina State University – Fall Insect Behavior](https://content.ces.ncsu.edu/fall-insect-behavior)
Common Insects That Increase in the Fall
1. Boxelder Bugs
Boxelder bugs are small, black and orange insects that are notorious for invading homes during the fall. They seek warmth and often congregate in large numbers around sunny spots on buildings. These insects primarily feed on the seeds and leaves of boxelder trees. As their food supply dwindles, they look for shelter indoors, leading to significant infestations. Boxelder bugs can be a nuisance, especially when crushed, as they emit a strong odor.
**Prevention Tip**: Seal any cracks or gaps around windows and doors, and consider using screens to block their entry. [University of Minnesota Extension – Boxelder Bugs](https://extension.umn.edu/insects-in-minnesota/boxelder-bugs)
2. Ladybugs
As the weather cools, ladybugs seek shelter to overwinter, often gathering in large clusters in warm areas of homes. While ladybugs are beneficial for gardens, as they consume aphids and other pests, their increased numbers indoors can be an annoyance for homeowners. They tend to prefer attics and wall voids, and when disturbed, they may release a yellow fluid that can stain surfaces.
**Prevention Tip**: Use caulk or weather stripping to seal potential entry points, particularly around windows and doors. [Colorado State University Extension – Lady Beetles](https://extension.colostate.edu/topic-areas/insects/lady-beetles/)
3. Ants
Many species of ants, including carpenter ants and odorous house ants, become more active in the fall as they prepare for winter. Carpenter ants may invade homes in search of food and nesting sites. They often build nests in wood, which can lead to structural damage if left unchecked. Ants are attracted to food sources, so kitchens and pantries are common targets.
**Prevention Tip**: Keep food sealed and clean up spills promptly. Regularly inspect for signs of nesting and treat infestations early. [University of California Agriculture and Natural Resources – Ants](http://ipm.ucanr.edu/PMG/PESTNOTES/pn74134.html)
4, Stink Bugs
Stink bugs are another pest that increases in fall activity. As temperatures drop, they seek out sheltered areas to hibernate. Unfortunately, this often leads them to invade homes, where they can become a nuisance. Their strong odor can be quite unpleasant when disturbed, leading to complaints from homeowners.
**Prevention Tip**: Inspect and seal cracks around windows, doors, and other potential entry points to reduce their chances of coming indoors. [Michigan State University Extension – Stink Bugs](https://www.canr.msu.edu/news/stink_bugs_hibernating_in_your_home)
5. Flies
Certain fly species, such as cluster flies, become more noticeable in the fall. These flies seek warm areas to hibernate, often finding their way into homes through small openings. Unlike house flies, cluster flies are sluggish and often cluster together in attics or walls during the cooler months. They can be particularly bothersome as they emerge on warmer days.
**Prevention Tip**: Use fly screens and ensure doors and windows are properly sealed to keep these pests out. [Virginia Cooperative Extension – Cluster Flies](https://www.pubs.ext.vt.edu/2906/2906-1314/2906-1314.html)
Types of Spiders Increase in the Fall
1. Black Widow Spiders
Black widow spiders, easily identifiable by their shiny black bodies and distinctive red hourglass markings, are more frequently spotted in the fall as they seek shelter for the winter. They prefer dark, undisturbed areas, making garages, sheds, and even basements ideal locations for nesting. Female black widows are known for their venomous bites, which can pose significant health risks. As the weather cools, they may also wander indoors in search of warmth and prey.
**Prevention Tip**: Keep clutter to a minimum, especially in dark areas, and regularly check for spider webs. If you suspect an infestation, contact a pest control professional. [University of California Agriculture and Natural Resources – Black Widow Spiders](http://ipm.ucanr.edu/PMG/PESTNOTES/pn74127.html)
2. Hobo Spiders
Hobo spiders are another species that become more active in the fall. Known for their fast movements and distinctive leg length, these spiders often venture indoors as they search for mates and suitable nesting sites. Hobo spiders prefer to hide in corners and cluttered areas, which can pose a risk if disturbed. While their bites are generally not life-threatening, they can cause significant irritation.
**Prevention Tip**: Vacuum regularly to remove webs and egg sacs, and consider using traps in areas where you’ve seen spider activity. [Washington State University Extension – Hobo Spiders](https://extension.wsu.edu/pests/hobo-spider/)
Conclusion
Understanding why different insects and spiders increase in the fall can help you take proactive measures to protect your home. By being aware of these pests and their behaviors, you can implement effective prevention strategies, such as sealing entry points and keeping your living spaces clean. This knowledge will not only help you maintain a comfortable home but also minimize potential pest-related issues as the seasons change. Taking these steps now will ensure a more pest-free environment as you transition into the colder months.
For additional insights on fall cleanup and winterization recommendations.