When the rains return to Costa Rica, so does an explosion of life — from lush green forests to, yes, plenty of rainy season bugs. Whether you love spotting critters or just want to know what to expect, here’s a guide to some of the most common insects you’ll encounter during the rainy season.
Why Bugs Love the Rainy Season
The rainy season (roughly May through November) creates the perfect conditions for insects — warm temperatures, abundant water, and dense vegetation. While this means more encounters with bugs, it also means more butterflies, birds, and the animals that rely on them. It’s all part of Costa Rica’s incredible ecosystem!
Mosquitoes
Let’s get this one out of the way! Mosquitoes are more active during the rainy season, especially near standing water. While most mosquito bites are just itchy and annoying, there is occasional risk of diseases like dengue in some areas.
Tips:
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Wear long sleeves and pants in the evening.
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Use insect repellent (DEET or picaridin-based are most effective).
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Sleep with a fan or mosquito net if needed — they hate moving air!
Spiders
Costa Rica is home to many spider species, from tiny orb weavers to large (but usually harmless) tarantulas. They’re great for controlling insect populations and are rarely aggressive. You’ll most likely see them at night or in quiet corners of gardens and lodges.
Tips:
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Shake out shoes and clothes before putting them on, especially in rural areas.
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Enjoy them from a distance — they’re fascinating architects!
Caterpillars
Rainy season brings a boom in caterpillars as butterflies and moths lay their eggs. Many are harmless and beautiful, but a few, like the Lonomia obliqua (known locally as the “stinging caterpillar”), can cause skin irritation if touched.
Tips:
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Teach kids not to handle fuzzy or spiny caterpillars.
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Admire their incredible colors and patterns — they’re future butterflies!
Butterflies & Moths
Here’s the fun part! Costa Rica’s rainy season is butterfly season, with species like the iconic Blue Morpho flashing through the forests. At night, you’ll see moths drawn to lights — some as big as your hand!
Tips:
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Visit butterfly gardens or simply sit outside and enjoy nature’s show.
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Turn off unnecessary lights at night to avoid attracting moth swarms.
No-see-ums (Biting Midges)
These tiny, almost invisible pests can pack an annoying bite, especially near beaches and mangroves at dawn and dusk.
Tips:
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Use the same precautions as for mosquitoes: repellent, long clothing, fans.
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Baby oil or coconut oil on ankles and feet can create a barrier — a local trick!
Bottom Line
Yes, the rainy season means more bugs — but they’re part of what makes Costa Rica’s ecosystems so vibrant and alive. With a few simple precautions, you can enjoy your adventure and leave the biting bugs behind.
Quick Packing List for Bug Protection
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Bug spray (DEET or picaridin)
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Lightweight long sleeves & pants
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A good hat
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Anti-itch cream or aloe gel
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Optional: travel mosquito net
