Gaucher July 2022 Top

Spiders and webs: their halachos and biology

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Feb 22, 2011

The spring and summer months have some unique halachos, including one’s interactions with HaShem’s creatures, such as spiders and their webs.

“Every creeping creature that creeps upon the ground - it is an abomination, it shall not be eaten. Everything that creeps on its belly and everything that walks on four legs, up to those with numerous legs. Among all the creeping things that creep upon the earth, you may not eat them, for they are an abomination. Do not make yourselves abominable by means of any creeping thing; do not contaminate yourselves through them, lest you become contaminated through them” (Vayikra 11:41-43). These verses are the source forbidding the eating of spiders, as well as other creeping creatures. There are cultures, such as those in South America (excluding, Chile, Brazil, Uruguay, and Argentina) and in Papua New Guinea, who include spiders in their traditional foods (Wikipedia, retrieved 2/20/2011).

According to the Yalkut Shimoni, a midrashic anthology of Tanach, attributed to Rav Shimon HaDarshan of Frankfurt (13th century), the spider is the most hated of the creeping creatures (Mishlei, 30, simon 964). Eight centuries later, the spider is still concerned the most feared of the creeping creatures. The fear of spiders (or, arachnophobia) ranked as number one of the 10 most common phobias, affecting 50% of women and 10% of men (Cherry, retrieved 2/18/2011). Upon seeing a spider, an arachnophobic person may either freeze or scream and flee. Such an individual may be unable to trap or kill the spider, relying upon others to rid the spider (Fritscher, 2009). Rav Moshe Feinstein held that that if insects, which would include spiders, are disturbing a weekday meal, it is permissible to kill them. However, this must be done in a manner that is without cruelty and that brings “honor to the Torah” (Igros Moshe, Choshen Mishpat, volume 2, simon 47, #1).

Spiders are classified as air-breathing arthropods, with approximately 40,000 different species. Externally, the spider appears as two anatomical segments, an anterior cephalothorax and a posterior abdomen. The head region, or cephalothorax, has 2 sets of appendages, a pair of chelicerae ahead of the mouth and a pair of pedipalps behind the mouth. The chelicerae terminate in fangs, used to inject venom into prey from venom glands at their base; the pedipalps act as an extension of the mouth. Interesting, the gut of the spider is too narrow to take in solid foods and can only handle liquefied materials. To accomplish this, spiders utilize two types of external digestion. In one type of external digestion the spider pumps digestive enzymes into the prey, which dissolve the innards of the prey, which is then sucked into the spider’s gut, leaving behind the empty shell of the prey. In the second type of external digestion, the chelicerae and pedipalps hold the prey and grind it into a pulp mass, while pumping in digestive juices to liquefy the mass (Wikipedia, retrieved 2/18/2011).

The posterior portion of the spider, the abdomen, contains four pairs of legs. The back portion of the abdomen contains spinnerets that extrude liquid silk proteins which quickly solidify into silk fibers used to construct the webs, either appearing as orbs or as tangled cobwebs, used to capture their prey. A midrash cites that Dovid, as a shepherd caring for his father’s sheep, once observed a spider building a web. Although awed of the spider’s industrious accomplishments, he questioned HaShem as to the purpose of creating spiders. HaShem responded that the day will come when Dovid would understand the purpose of spiders. Later in his life, when fleeing from King Saul’s army, Dovid hid in cave, but realized that he would soon be discovered. However, suddenly a spider emerged and constructed a huge web blocking the entrance to the cave. When King Saul’s army arrived at the cave’s entrance and viewed the unbroken spider web, they understood that Dovid could not possibly have entered to hide in that cave. The question of HaShem’s creating seemingly useless creatures was also discussed in Shabbos (77b), with Rav Yehudah providing a rationale for spiders. Apparently, spiders provide a cure for the sting of a scorpion; as explained by Rashi, one crushes the spider and places it upon the place of the scorpion’s sting. More recently, chemicals isolated from spiders have been shown to have medicinal properties. For example, venom of the South American tarantula (Grammostola spatulata) contains a peptide that can calm irregular heartbeat induced by stress (Coffey, 2011). In addition, spiders are components of ecological food webs, serving as predators to control insect populations and serving as prey for other creatures.

Spiders are mentioned briefly in Nach. Iyov (8:14), “That on which he placed his strong unshakable confidence will be cut down and that on which he placed trust will become a spider’s web.” Rav Shimon Schwab suggested that this pasuk referred to a fool who cannot change his mind in the face of intellectual persuasion or great danger. For such a person, his strong self confidence in himself is his downfall, i.e., his self confidence is flimsy as a spider web. Another thought is that this pasuk referred to a wicked person who placed all his faith in his “home,” which, as a spider’s web, will not last (see Job, Mesorah Publ. Ltd., Brooklyn, NY). As noted in Mishlei (30:24), there are four small creatures who, despite their insignificant size, are exceedingly wise. One of the four is the spider, “the spider with her hands grasps and she is in the king’s palace (Mishlei 30:28). Rashi explained this as, “with her hands, she grasps and clings to the walls.” Mezudath David interpreted this pasuk to provide a moral lesson, that the spider sustains herself with her own handiwork (i.e., catching flies in her web), without relying on others for support (i.e., although found in the king’s palace, she avoids royal delicacies). Ibn Nachmiash noted that although the spider is weak and can be easily grasped, it is found in exalted places, such as in the palace of the king (see The Book of Proverbs, Judaica Press, NY). The Yalkut Me’Am Loez (see The Torah Anthology, Proverbs, II, Moznaim Publ. Corp. NY) extended the idea presented by Ibn Nachmiash, in that although Am Yisrael is hated in the eyes of the nations, nevertheless, Jews obtain positions of prominence in the political arena (e.g., Yosef in Pharoah’s court; Mordechai in the palace of Ahassuerus, and Daniel, Ezra, and Nechemiah elevated in the palaces of the Babylonians and Persians). As an aside, Me’Am Loez noted that the first letters of the Hebrew phrase “the spider with her hands grasps” spells “Shabbos,” hinting that when cleaning for Shabbos, one must remove spider webs.

Spiders are noted in Tehillim and in Isaiah, with the focus on their venom. Tehillim (140:4), “They whetted their tongue like a serpent; the venom of an akhshuv is under its lips.” Although there are various interpretations of akhshuv, the Tosefta to Parah (9:6) included it among the spiders. Here, the wicked are compared to spiders, who capture their prey, kill them with venom, and dissolve them to a pulpy mass which is sucked into the spider’s gut (Feliks, 1981). Isaiah (59:5), “They hatch the viper’s eggs and weave the spider’s web.” The prophet was referring to those who deceit others, “they weave the spider’s web” to ensnare their victims, render them defenseless, and proceed to “suck their blood” (Feliks, 1981). The Redak added that just as a spider’s web has no permanence, so to the activities of the wicked will not avail them.

In Perek Shirah the spider says, “Praise Him with sounding cymbols! Praise Him with loud clashing cymbols!” (Tehilim 150:5). Rabbi Nosson Slifkin (2001) wrote that “the song of the spider is the triumphant sound of the one who has made it to the royal palace by virtue of his cleverness, overcoming the hatred that many feel towards him. It is the song of the royal instruments.”

A surprise to me was that there are many halachos regarding spider webs. In the Shulcan Oruch (259:1) the following is cited: “A person should rise early on Friday, so as to prepare the requirements for Shabbos. Even if one has many retainers at is his service, one should try to prepare personally something of the Shabbos needs, so as to thereby honor it.” On this, the Mishnah Berurah commented, “one should remove spider webs from the house on eruv Shabbos.” This idea was reinforced later in Shulcan Oruch (262:1): “One should cover his table, spread his couches, and prepare the entire house so that when he comes home from synagogue, he will find it arranged and ordered.” Again, the Mishnah Berurah added, “It would be good to clear away any spider webs from the house while it is still day (eruv Shabbos), so as to clean the house in honor of Shabbos.”

Another set of halachos are applicable to spider webs found on Shabbos. Rabbi Yehoshua Neuwirth (1989) in section (23:9), “Housekeeping and use of domestic facilities on Shabbos and Yom Tov,” codified the following halachos. “Cobwebs on furniture or some other movable article may be removed, provided that this is done not with one’s hands, but with a broom or some other instrument. One should not remove cobwebs from the walls, the ceiling, or any other part of the home, both (1) because the cobwebs themselves are muktzeh and (2) because doing so is analogous to the forbidden activity of detaching something which is connected to the ground. If one finds a spider, one is of course not allowed to kill it on Shabbath or Yom Tov.” Apparently, the Sephardic viewpoint is slightly different, as Rabbi Abraham HaCohen Soae (2005) noted the following: “It is permitted to gently remove a spider web from the wall on Shabbat, provided one is careful not to kill the spider on Shabbat. Other poskim forbid removing a spider web on Shabbat because it is included in the forbidden act of uprooting, tolesh min hamechubar.”

The issur of killing a spider on Shabbos is also discussed in the Mishnah Berurah. As noted in Shulcan Oruch (316:10) regarding the melocha of trapping on Shabbos: “One may kill any animal or creeping creature on Shabbos whose bite is definitely fatal, even if it is not running after him. As regards other destructive creatures, such as snakes or scorpions in a locality where their bites are not fatal, if they are running after one it is permitted to kill them, but if not, it is forbidden. However, it is permitted to trample on them casually even with intent, provided one makes it appear unintentional.” On this the Mishnah Berurah added, “It is forbidden to kill a spider on Shabbos. Even though everyone says that it is dangerous, if it falls into food, it is nevertheless not certain to cause harm and one can cover the food. Therefore, one should protest against those who kill spiders on Shabbos.” The Ba’er Hativ added that there was a small chance that a spider in food constituted a danger.

Apparently, the key phrases are “definitely fatal” and “running after one.” Spider venom is harmful, but not fatal, to humans and spiders do not chase after humans. According to Encyclopaedia Judaica, there are hundreds of species of spider in Israel, all with venomous fangs, but the poison is mild. Hadassah Medical Organization described the clinical symptoms of bites from two species of spiders common to Israel, the black widow spider and the brown recluse spider. Reactions to a bite from a black widow spider include pain and burning at the site of the bite, followed by cramping, restlessness, anxiety, and muscle cramping especially in the stomach; advanced symptoms include heavy sweating, high blood pressure and weakness in the legs. Treatments involve pain medication, muscle relaxants and, if needed, administration of antivenin. A bite from the brown recluse spider causes extensive local tissue destruction and, in rare cases, the venom can cause blood coagulation; medical treatment is correlated to the severity of the symptoms. In the mid 1990s, an outbreak of brown recluse spider bites was noted in workers in citrus groves of the Arava valley in southern Israel (Borkan et al., 1995). Spiders do not chase people. As noted by Hadassah Medical Organization, “spider bites most often occur when a spider becomes caught in clothes, and then the clothes are worn. Spiders do not go out of their way to bite, but only bite to defend themselves.” Over the 1993 to 1997 period, spider and scorpion bites were reported in the soldiers of Israel Defense Forces, occurring at a rate of 1,478 per 100,000 soldiers, primarily in the spring and summer months, and with no reported fatalities (Haviv et al., 1998).

Techniques in biotechnology were used to splice spider silk protein-producing genes into two types of mammalian cells (bovine mammary epithelial cells and hamster kidney cells) grown in culture, thereby permitting the production of spider silk fibers in Petri dishes. The recombinant silk proteins were harvested and spun into strong, lightweight fibers (termed, Biosteel). This research on spider silk fibers, conducted by Nexia Biotechnologies Inc. and the U.S. Army Soldier Biological Chemical Command, has military applications, such as in the construction of body armor and aircraft. Of additional interest was their creation of transgenic goats that carried spider genes to produce the silk proteins. As the genes are activated only in cells of the udder, the silk protein was obtained easily upon milking the goats (BBC News, 2000). The creation of transgenic animals to produce medically-important proteins is not new.

Biosteel has many potential medical applications. With a tensile strength greater than steel, yet 25% lighter than synthetic petroleum-based polymers, its greatest application is usage in products when strength and lightness are critical. As it is compatible with body tissues, usage of Biosteel includes the construction of artificial tendons, ligaments, and limbs and the creation of superthin, sutures for ocular surgery, neurosurgery (BBC, 2000), lip surgery, intraoral surgery, and for some skin wounds (Omenetto and Kaplan, 2010). Interestingly, the usage of spider webs for bandaging cuts was noted in the Shulcan Oruch (328:48): “It is forbidden to put a cloth on a bleeding wound on Shabbos, because the blood will dye it. And it is forbidden to extract blood from a wound. One should therefore wash the wound that one may wrap spider’s webs over the wound and cover all the blood and the entire wounded area with them and after that he may wrap a rag over the wound.”

What is the kashrus status of goat milk containing spider silk proteins? According to Rabbi Dr. Moshe Tendler, Rosh HaYeshiva, Rabbi Isaac Elchanan Theological Seminary of Yeshiva University and Professor of Biology, Yeshiva College, “(a) a spider web is not an “ochel” even for an animal; hence “issur v’heter” laws do not apply and (b) a gene does not carry the halachic signature of its origin” (personal communication, 2/21/2011).


Appreciation is expressed to Dr. Moishe Steier, noted pediatric cardiologist in Maimonides Hospital, Brooklyn, NY, for introducing me to the halachos of spider webs. Appreciation is also expressed to Rabbi Yisroel Reisman, Rav of Agudath Yisroel of Madison, Brooklyn, and to Rabbi Eli Babich, program director, Jewish Enrichment Center, Manhattan, for reviewing the Torah content of this article.


BBC News, August 21, 2000, GM goat spins web based future,

Borkan, J., Gross, E., Lubin, Y., and Oryan, I.,1995, An outbreak of venomous spider bites in a citrus grove, Am. J. Trop. Med. Hyg., 52:228-230.

Brooker, R.J., 2011, Genetics. Analysis & Principles, McGraw Hill Book Company, NY, NY

Cherry, K., Ten of the most common phobias, (retrieved 2/18/2011)

Coffey, R., 2011, 20 Things you didn’t know about spiders, Discover (March), p. 80.

Feliks, Y., 1981, Nature and Man in the Bible, Soncino Press, NY, NY

Fritscher, L., 2009, Spider fears or arachnophobia,

Hadassah Medical Organization (retrieved 2/20/2011), Spiders, scorpions, and snakes…. Oh my,

Haviv, J., Huerta, M., Shpilberg, O., Klemert, E., Ash, N., and Grotto, I., 1998,

Poisonous animal bites in the Israel Defense Forces, Public Health Rev., 26:237-245.

Neuwirth, Y.Y., 1989, Shemirath Shabbath, volume II, Feldheim, NY, NY

Omenetto, F.G. and Kaplan, D.L., 2010, New opportunities for an ancient material, Science 239:528-531.

Schwab, S., 2005, Rav Schwab on Iyov, Mesorah Publ. Ltd., Brooklyn, NY

Service, R.F., 2002, Mammalian cells spin a spidery new yarn, Science 295:419-420.

Slifkin, N., 2001, Nature’s Song, Targum/Feldheim Press, Southfield, MI.

Soae, A. HaCohen, 2005, Practical Laws of Shabbat, part II, The Aharon HaCohenInstitute, Israel (see p. 144).

Wikipedia (retrieved 2/18/2011, Spider,

Wikpedia (retrieved 2/20/2011), Arachnophobia,


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