For many people, spiders belong on the list of “creatures to avoid.” These secretive, creepy-crawly arachnids seem to lurk in dark places and drop down from out of nowhere, invading our living space. At the sight of a spider, some of us run and hide. Others will sprint for the nearest shoe or tissue.
Although a few species of spiders truly are something to be feared, like black widows and tarantulas, the majority of spiders present no danger to us humans. In fact, without spiders, our world would be completely overrun by insects.
A few facts about spiders
There are two types of spiders: web-building spiders and hunting spiders. Web-building spiders spin strong nets of sticky silk to capture the unfortunate insects who happen to get too close. Hunting spiders use speed and keen eyesight to chase and capture their prey.
Most species of spiders are carnivores. Roaches, earwigs, flies, fleas, moths, and other common household pests can all be reduced in and around your home, thanks, in part, to the spider’s diet.
In a recent study published in The Science of Nature (2017), scientists published some shocking estimates about the amount of insects consumed by spiders each year. Researchers used two separate methods for their calculations with both yielding similar results.
They estimated that spiders consume between 400 – 800 million tons of prey each year! To put this into perspective, humans eat approximately 400 million tons of meat and fish annually.
Mosquitoes: another pesky insect
Mosquitoes are another common insect found in and around our homes. Although mosquitoes can be extremely bothersome, the real issue with mosquitoes has to do with their direct role in spreading deadly diseases. Malaria, West Nile virus, Zika virus, and several others are easily spread from person to person through mosquito bites.
Do spiders eat mosquitoes?
Spiders will generally eat anything that gets caught in their web. If a mosquito gets snared in a spider’s web, it will most certainly become the spider’s next meal. That being said, the vast majority of spiders will not single out or prefer certain insects over others.
However, two very unique species of spiders have been identified. These spiders are considered to be mosquito-specialist spiders. They have been observed extensively and research has concluded these two species consistently seek out and prefer mosquitoes over other insects.
Otherwise known as the “vampire spider,” this spider is found near Lake Victoria in East Africa. These spiders have fascinating characteristics:
- E. culicivora have unique, complex eyes that give them extraordinary vision. They use this vision to identify and stalk their prey.
- These spiders have a keen sense of smell; studies have proven these spiders can single out their prey using smell alone.
- Classified as “jumping spiders,” they can jump between 10 to 40 times their own body length.
- In research studies and in the field, E. culicivora consistently chose blood-filled female mosquitoes over other more abundant insects, including male mosquitoes (who do not bite), and non-fed females. Furthermore, they seem to prefer the Anopheles mosquito, which is the species responsible for spreading malaria.
- Scientists believe they prefer blood-filled mosquitoes for mating purposes. The blood becomes a perfume-like scent, helping them to attract a potential mate. They lack specialized mouthparts needed to bite humans and animals, so they must consume their blood through mosquitoes.
- These spiders prefer to live indoors, on the walls of people’s homes.
This jumping spider is found in Malaysia. It prefers to live in and around bamboo. While E. culicivora seeks after blood-filled female mosquitoes, P. wanlessi opts for mosquito larvae in pools of water.
Could spiders be used to help control the mosquito population?
Mosquitoes continue to spread dangerous diseases in our world, despite our best efforts to control them. A research review, published in the International Journal of Mosquito Research (2018), stated that developing more ways to control mosquitoes using their natural enemies is critical.
Mosquitoes and other insects are becoming resistant to insecticides, decreasing their effectiveness. In areas where mosquitoes run rampant, especially the tropical and subtropical regions, resources are often limited. Many times, insecticides are not readily available.
Sometimes, the insects that benefit the environment are inadvertently killed. This includes spiders, ants, and other natural enemies of the mosquito.
Researchers concluded that it would be helpful to preserve natural enemies (like E. culicivora and P. wanlessi) and possibly even bolster their numbers in an attempt to help control the mosquito population.
A real-life example:
In 2010, heavily-flooded regions of Sindh, Pakistan, saw first-hand the effect spiders can have on the mosquito population. As flood waters rose, massive amounts of spiders fled to the trees.
The trees, teeming with spiders, became completely enshrouded in spider webs. Despite stagnant flood waters in the area, local residents reported decreased numbers of mosquitoes. It was theorized that the mosquitoes were getting caught in the spider webs. Unfortunately, the trees did not fare so well.
The majority of spiders will happily eat a mosquito meal if one shows up on its doorstep. And, although each one eaten is one less mosquito in the world, it is unlikely that the average spider will be able to significantly reduce the mosquito population. Spiders do an excellent job of keeping all insect populations under control, but they do not tend to single out or prefer particular insects.
However, for tropical and subtropical regions where mosquitoes are rampant, preserving mosquitoes’ natural enemies becomes critical. Educating local communities about mosquito-specialist spiders like E. culicivora and P. wanlessi may help bolster their numbers, making more of an impact in the war against mosquitoes.
A spider like E. culicivora may seem especially frightening. A large spider with beady eyes that jumps down from the wall will likely be killed. However, if people are educated about its importance in the environment, its inability to bite, and its unique preference for mosquitoes, they may be more likely to keep them around.