Spiders are not insects, they are arachnids, yet are similar to insects in size and a few other respects…nonetheless, the main food source of SPIDERS are「insects, bugs.」「Insects inform, make aware」the spider of their presence by actuating various「silk-like, silk spinning」web strands when struggling to free themselves after becoming ensnared and later「engulfed」in the spider's「cloud-like cocoon」of web strands when stored for later ingestion. SPIDERS puncture the body of still-living victims with an「arrow-like mouth」and then「suck, drink internally, absorb」liquified bodily fluids and meat for nourishment:
「As a first step in eating, the spider will literally vomit digestive fluid over the prey. Then the prey is chewed with the 'jaws' (chelicerae), and the fluid is sucked back into the mouth together with some liquefied 'meat' from the prey. The spider repeats this process as often as necessary to digest, and ingest, all but the inedible hard parts.」
[ https://www.burkemuseum.org/collections-and-research/biology/arachnology-and-entomology/spider-myths/myth-spiders-only-suck/ 2019-06-28 ]
As a「bug that knows」and by applying a sexual connotation to each of the three major elements:「In most cases of spider mating, sex pheromones are emitted by the female and received by the male. Female spiders directly release sex pheromones from their body cuticle or web silk. …Male spiders are often choosy and prefer virgin females (Gaskett, 2007). The first mating with a female is important as possible future concerns include: sperm priority and future males may be disinterested in a female that is not a virgin (Gaskett, 2007).」
[ https://en.wikipedia.org/wiki/Sex_pheromone 2013-09-05 ]
It seems as if male spiders do not want to contract any problems due to prior matings of a female partner with other males…the same is true for humans—well, some humans…others aren't so picky.
「Insect down from heaven, silk spinning」with「head sliding and orifice」seems to describe the manner in which a SPIDER begins to build its web, by spewing sticky threads as do silk caterpillars while appearing to slide down the first vertical thread. A hole, or orifice, remains in the center of most webs where the spider sits and waits for prey.

External source definitions …excluding politically incorrect concepts and other meanings deemed offensive today; may include extended definitions, euphemisms, and mnemonics)
Chinese: see 蜘蛛
Japanese EDRDG: spider
Unihan extended: spider