蛛

Left insect radical - originally a pictograph of a curled-up snake or worm, generalized in Chinese to cover all small crawling creatures including arachnids. Indexes 蛛 in the bug family alongside 蚁 ant, 蜂 bee, 蛇 snake, 蝶 butterfly. Spiders aren't insects biologically, but Chinese taxonomy lumps them under 虫.

Right 朱 supplies the sound, identical pinyin zhū with no drift. Same phonetic family: 株 tree-trunk, 珠 pearl, 诛 to execute. 朱 itself originally pictured the red core of a tree - here it carries no meaning, just the sound clip for the spider word 蜘蛛.