12: Butterfree 14: Kakuna

Weedle

13: Weedle

Kanto

	HeartGold	SoulSilver	FireRed	LeafGreen	Yellow	Red	Blue
Walking in tall grass or a cave
Patern Bush			10% L6	10% L6
Route 2			5% L4–5	5% L4–5
Route 2 north, towards Pewter City		1% L4 +20% L3 +10% L3 +10% L3 +10% L5
Route 2 south, towards Viridian City		1% L4 +20% L3 +10% L3 +10% L3 +10% L5				15% L3–5
Route 24						20% L7
Route 24			20% L7	20% L7
Route 25			20% L8	20% L8
Route 25						20% L8	1% L8
Viridian Forest			40% L3–5	40% L3–5
Viridian Forest		+40% L3 +40% L3				45% L3–5	5% L3

Johto

	HeartGold	SoulSilver
Walking in tall grass or a cave
Ilex Forest		+20% L5 +40% L5–6 +30% L5–6 +20% L5–6
National Park		+20% L10 +20% L10 +30% L10–12 +10% L10
Route 30		+20% L3 +25% L3–4 +30% L3–4 +10% L3
Route 31		+20% L4 +25% L4–5 +10% L4 +10% L4
Unknown; all bugs		100% L10–14

Sinnoh

	Platinum	Diamond	Pearl
Walking in tall grass or a cave
Eterna Forest	+4% L13
Route 204 north, towards Floaroma Town	+8% L10
Route 204 south, towards Jubilife City	+8% L5	+8% L6	+8% L6