The reactions of arachnophobics are often irrational (though not all arachnophobics acknowledge this irrationality). It is one of the most common specific phobias, and some statistics show that 50% of women and 10% of men show symptoms. It may be an exaggerated form of an instinctive response that helped early humans to survive, or a cultural phenomenon that is most common in predominantly European societies.
The fear of spiders can be treated by any of the general techniques suggested for specific phobias. As with all phobias, the strength of the associations means the individual must not actively pursue the consequences, and outsiders should not in any way undermine and "play" with the phobia in the meantime.
Symptoms and effect 
People with arachnophobia tend to feel uneasy in any area they believe could harbor spiders or that has visible signs of their presence, such as webs. If arachnophobics see a spider, they may not enter the general vicinity until they have overcome the panic attack that is often associated with their phobia. Some people scream, cry, have trouble breathing, have excessive sweating or even heart trouble when they come in contact with an area near spiders or their webs. In some extreme cases, even a picture or a realistic drawing of a spider can also trigger fear.
Arachnophobia can be triggered by the mere thought of a spider or even by a picture of a spider in some cases. Some arachnophobics will, on entering a room, search it for a spider. If they find one they will monitor its progress very thoroughly. Others will do all in their power to distract themselves to avoid seeing the spider.
Evolutionary reason 
An evolutionary reason for the phobias, such as arachnophobia, claustrophobia, fear of snakes or mice, etc. remains unresolved. One view, especially held in evolutionary psychology, is that the presence of venomous spiders led to the evolution of a fear of spiders or made acquisition of a fear of spiders especially easy. Like all traits, there is variability in the intensity of fears of spiders, and those with more intense fears are classified as phobic. Spiders, for instance, being relatively small, don’t fit the usual criterion for a threat in the animal kingdom where size is a factor, but nearly all species are venomous, and although rarely dangerous to humans, some species are dangerous.
Arachnophobes will spare no effort to make sure that their whereabouts are spider-free, hence they would have had a reduced risk of being bitten in ancestral environments. Therefore, arachnophobes may possess a slight advantage over non-arachnophobes in terms of survival. However, this theory is undermined by the disproportional fear of spiders in comparison to other, potentially dangerous creatures that were present during Homo sapiens environment of evolutionary adaptiveness. Studies with crickets have shown that a fear of spiders can develop before birth.
Scientists suspect humans may be born with a fear of spiders and snakes, which are healthy phobias that improve the odds of survival in the wild. It's not known how such an inborn fear might develop, however. Now researchers have proven that unborn crickets can gain a fear of spiders based on their mother's harrowing experiences. In humans, research also suggests the widespread fear of spiders and snakes (arachnophobia and ophidiophobia, respectively) may be innate. A study in 2008 found that both adults and children could detect images of snakes or spiders among a variety of non-threatening objects more quickly than they could pinpoint frogs, flowers or caterpillars.
In the Dark Ages spiders were commonly considered to be a source of contamination of food and water.
The alternative view is that the dangers, such as from spiders, are overrated and not sufficient to influence evolution. Instead, inheriting phobias would have restrictive and debilitating effects upon survival, rather than being an aid. For some communities such as in Papua New Guinea and South America (except Chile, Colombia, Brazil, Uruguay, Argentina and Bolivia), spiders are included in traditional foods. This suggests arachnophobia may be a cultural, rather than genetic trait. In western societies as many as 55% of females and 18% of males are estimated to experience arachnophobia.
Arachnophobia affects 3.5 to 6.1 percent of the population. The first line of treatment is systematic desensitization – also known as exposure therapy – which was first described by South African Psychiatrist Joseph Wolpe. In addition beta blockers, serotonin reuptake inhibitors and sedatives are used in the treatment of phobias.
Before engaging in systematic desensitization it is common to train the individual with arachnophobia in relaxation techniques. Systematic desensitization can be done in vivo (with live spiders) or by getting the individual to imagine situations involving spiders, then modelling interaction with spiders for the person affected and eventually interacting with real spiders. This technique can be effective in just one session. The discovery of the implication of N-methyl-D-aspartate in fear and fear extintion has led to the use of D-cycloserine—originally developed as an antibiotic—to augment the results of therapy.
Recent advances in technology have enabled the use of virtual or augmented reality spiders for use in therapy. These techniques have proven to be effective. There is an iOS app currently in development using games and augmented reality to treat arachnophobia.
Notable people with arachnophobia 
- Justin Timberlake
- Kim Kardashian
- Dario Perez
- Kirsten Dunst
- Chloë Grace Moretz
- Rupert Grint
- Frank Iero
- Emma Stone
- Jessica Simpson
- Phill Jupitus
- Andre Agassi
- Simon Pegg
- J.K Rowling
- Ricky Gervais
- Miranda Cosgrove
- Victoria Justice
- Matt Bellamy[better source needed]
- J.R.R Tolkien
- Peter Jackson
See also 
- Heather Hatfield. "The Fear Factor: Phobias". webmd.com
- "A Common Phobia". phobias-help.com. Archived from the original on 2009-08-02. Retrieved 2009-08-02. "There are many common phobias, but surprisingly, the most common phobia is arachnophobia."
- Lisa Fritscher (2009-06-03). "Spider Fears or Arachnophobia". Phobias. About.com. Archived from the original on 2009-08-02. Retrieved 2009-08-02. "Arachnophobia, or fear of spiders, is one of the most common specific phobias."
- "The 10 Most Common Phobias — Did You Know?". 10 Most Common Phobias. Archived from the original on 2009-08-02. Retrieved 2009-08-02. "Probably the most recognized of the 10 most common phobias, arachnophobia is the fear of spiders. The statistics clearly show that more than 50% of women and 10% of men show signs of this leader on the 10 most common phobias list."
- Friedenberg, J., and Silverman, G. (2005). Cognitive Science: An Introduction to the Study of Mind. SAGE. pp. 244–245. ISBN 1-4129-2568-1. Retrieved 2008-10-11.
- Davey, G.C.L. (1994). "The "Disgusting" Spider: The Role of Disease and Illness in the Perpetuation of Fear of Spiders". Society and Animals 2 (1): 17–25. doi:10.1163/156853094X00045.
- "Fear of Spiders - Arachnophobia". Disabled World. January 18, 2009.
- Gerdes, Antje B.M.; Uhl, Gabriele; Alpers, Georg W. (2009). "Spiders are special: fear and disgust evoked by pictures of arthropods". Evolution and Human Behavior 30: 66. doi:10.1016/j.evolhumbehav.2008.08.005.
- "Fear of spiders can develop before birth". MSNBC. 2010-02-18. Retrieved 19 February 2010.
- "Fear of Spiders Can Develop Before Birth". Live Science. February 18, 2010.
- Wagener, Alexandra L. and Zettle, Robert D. (2011). "Targeting Fear of Spiders With Control-, Acceptance-, and Information-Based Approaches". The Psychological Record 61 (1).
- Ohman, A; Mineka, S (2001). "Fears, Phobias, and Preparedness: Toward an Evolved Module of Fear and Fear Learning". Psychological review 108 (3): 483–522. doi:10.1037/0033-295X.108.3.483. PMID 11488376.
- Schmitt, WJ; Müri, RM (2009). "Neurobiologie der Spinnenphobie". Schweizer Archiv für Neurologie 160 (8): 352–355.
- Wolpe J. (1961). "The systematic desensitization treatment of neuroses". Journal of nervous and mental disease 132 (3): 189–203. PMID 13786444.
- "Phobia Treatments and drugs". Mayo Clinic.
- Ost, L. G. (1989). "One-session treatment for specific phobias". Behaviour research and therapy 27 (1): 1–7. PMID 2914000.
- Bouchard, S.; Côté, S.; St-Jacques, J.; Robillard, G.; Renaud, P. (2006). "Effectiveness of virtual reality exposure in the treatment of arachnophobia using 3D games". Technology and Healthcare 14 (1): 19–27.
- Kim, J., ed. (2011). Virtual Reality. InTech. ISBN 9789533075181.
- "Phobia Free". Virtually Free.
- "What makes Justin Timberlake anxious?". Celebrities with diseases. December 27, 2009.
- Oldenburg, A. (April 4, 2012). "Emma Stone does not like spiders". USA Today.
- "Simon Pegg conquers fear of spiders". OK!. June 8, 2012.
- "J. K. Rowling Is Scared Of Spiders". boldsky. December 5, 2008.
- Stiemerling, D. (1973). "Analysis of a spider and monster phobia". Z. Psychosom Med Psychoanal 1973 (4): 327–45. (German)
- National Geographic: Fear of Spiders rooted in Evolution