You find spiders in MySims by prospecting the Desert cemetery, near the Ghost Cave.
The spider is a Spooky essence, so it fits the eerie Desert area and the darker requests that ask for creepy crafting items.
Once the Desert is open, you can use the graveyard and nearby landmarks to keep your search focused.

Exact Spider Location In The Desert

You find the spider essence in the Desert cemetery, close to the Ghost Cave.
The Desert is an arid zone with bones, buried objects, and a graveyard, which matches the spooky theme of the spider essence in MySims according to the Spider | MySims Wiki | Fandom.
Find The Graveyard Near The Dinosaur Fossil Area
Head into the Desert and look for the area with the dinosaur fossil and skeleton details.
The graveyard sits nearby, and that is the spot you want for spider essence.
Prospect The Graveyard For Spider Essence
Use prospecting on the graveyard tiles until the spider appears.
Since spider is an essence, it behaves like other buried finds in the Desert, so keep scanning the essence locations around the cemetery for the best chance.
Use The Mausoleum Cave As A Landmark
If you lose your bearings, use the mausoleum cave area as your landmark.
From there, the graveyard and the nearby ghost themed spots are easy to find again.
What You Need Before The Spot Becomes Available

You cannot reach the Desert right away.
You need the right town square progress, the proper tools, and a little patience before the spider spot opens up.
Desert Access And Star Level Progress
The Desert opens at Star Level 3 after you get the pickaxe and clear the blocked path, as noted in the Desert (MySims) wiki entry.
Before that, the area stays locked.
How Prospecting Works In MySims
Prospecting lets you search buried spots for objects, living things, and other hidden essences in MySims.
When you see the right dirt patch or graveyard area, use prospecting and wait for the result.
Why Spider May Not Show Up Right Away
The spider does not always appear on the first search, so keep checking the same graveyard tiles.
The spawn can feel random, so repeated prospecting is normal.
Other Useful Essences To Grab While You Are There

The Desert and nearby maps offer more than spider.
You can pick up spooky items, gems, food, flowers, and a few fun extras while you are in the right area.
Nearby Graveyard And Cave Picks
In the graveyard zone, look for ghost, voodoo doll, and black rose.
You can also find amethyst, sapphire, amber, topaz, jade, and garnet while you work through the cemetery.
Hilltop And Orchard Desert Finds
Around nearby outdoor spots, you may spot lime, lemon, sunflower, yellow crayon, and red crayon.
These are useful if you want to stack a few different requests in one trip.
Junkyard, Fun Cave, And Fishing Dock Extras
The Desert also pairs well with the junkyard, Fun Cave, and fishing areas for items like tina doll, tim doll, elephant, puppy, tiger, hopi doll, pencil, globe, rocket, alien, star, robot, gears, diamonds, spades, hearts, clubs, kissing fish, fish bones, tiny shark, and gold.
If you are already traveling across town, gather as many of these as you can in one route.
How Spider Essence Is Used In Requests And Themes

Spider fits best in spooky-themed builds and requests.
It also pairs nicely with other eerie or themed essences when you want your crafting choices to match a clear style.
Spooky Recipes And Decoration Choices
Spider works well in spooky requests, and it can support cute, fun, or studious setups when the task calls for a mixed style.
You can use it alongside items like eyeball, black apple, thorn, dead wood, dark wood, light wood, metal, organic, and stone to build a stronger theme.
Matching Spider With Other Spooky Essences
Spider fits naturally with forest and forest essences when you want a creepy outdoor feel.
It also works with items such as be nice, musical note, soccer ball, magic carpet, action figure, video game, 8-ball, red apple, green apple, yellow blossom, rainbow trout, clown fish, tire, crab, octopus, and snake when a request mixes themes.
When To Farm More Than One
If you know a request needs spooky decor, grab more than one spider while you are in the Desert.
That saves time later. It also helps when you need related items like cherry blossom, plum blossom, rose, orange, chocolate cake, cake, gingerbread man, bacon, knight, or terra cotta for other builds.