Nobody really knows how many different species of insect there are in Costa Rica. The popular number to describe the diversity sits at 4000, but that seems extremely low according to several scientific claims. Another number that has been published is 300,000 different species, and while that seems ridiculous in comparison, it may be closer to the truth. Different species are being discovered every day, and the number of migrations going on at such a small level, in size relation to humans, are almost impossible to track.
Ants are the most predominant species of insect in Costa Rica. More species litter the ground than any other six legged creature, and they can be found across all regions of the country. 100 square acres of rain forest, a hectare, contains an average of 9 million ants. Army ants are the most voracious single species, partly proven by the fact indigenous peoples would use their bite to help suture wounds, discarding with the body of the ant once the pincers had clamped on.
Butterflies are a more lovely style of insect to discuss. Nearly 1000 species of these can be found in Costa Rica. Their brightly colored stylings are used as sexual attractants as well as to keep predators at bay. One thing is for sure, the number of butterflies in Costa Rica certainly draw in large numbers of enthusiastic tourists to seek them out. The scarabs, beetles, bees, stick bugs, and other crawlies just happen to be there as well.
Spiders are another major player in Costa Rica. These arachnids are as varied and intense as any other creature around. Several species are harmful to people, whether that means leaving them in severe pain or possibly killing them is another part of the question. Brazilian Wandering Spiders, alongside species related to Black Widows, have lethal reputations. Mostly, though, if you see something with eight legs, it is probably not harmful to anything but your ego if you happen to scream when you see it.