This item is a pretty poor choice for more junglers, so I have a suggestion to make it useful for some junglers while not great for all.

+50 attack damage
+14 health regen
+7 mana regen
+10% Spell Vamp

Unique Passive - Butcher: Damage dealt to neutral monsters increased by 25%.
Unique Passive - Incinerate: Basic attacks and damaging abilities (excluding damage over time) burn the target for 15-66 (based on level) true damage over 3 seconds.

Ten percent spell vamp on an AD item would be nice for those AD casters who jungle (Riven, Shyvana, Olaf even) while being a bad choice for AD DPS junglers (Master Yi, Tryn, probably Lee Sin since he likes the wriggles ward.)

Shyvana doesn't proc spellvamp except on her e, which is on a huge cooldown and scales with ap. Olaf can already get this idea to poke with axes, it's decently effective but wriggle's just has so much buff control. The 10% spellvamp isn't noticeable when he already has 22% from his W. RIven just rushes black cleaver for the burst, she doesn't need spellvamp, she needs lifesteal for her passive and pure AD for her shield.

Right now, it's only good on Darius, Urgot, Khazix, and Yorick.

doesnt one of the machete upgrades provide spellvamp or am i misinformed? and imo, its pretty balanced as it is.

It procs off of her W and R, but they only get 1/3 spellvamp (3.33%), which is 1/33 of damage dealt. This is equal to 3 health/second from W and 11 health from R. You would literally be better off building a Locket of the Iron Solari for sustain/shield instead of trying to spellvamp.

Spellvamp is good on champions with spammable single target spells (Jax, Vlad, etc). Shyvana doesn't, she's an autoattacker with a couple of high damage AOE spells.

EDIT: Wriggle's gives you 10% lifesteal. If you have 140 AD, this gives twin bite 28 hp healed every time it is off CD and 14 hp healed every autoattack. In dragon form, you get 28 hp per target you hit with twin bite. This is far superior to 10% spellvamp.