Monsanto Insectarium

The Monsanto Insectarium at the Saint Louis Zoo is one of the largest and most comprehensive insect exhibits in the country, housed in a dedicated indoor building that allows close-up viewing of hundreds of live invertebrate species. For families visiting the free Saint Louis Zoo, it's an unmissable indoor stop — particularly useful as a cool-down during summer heat or a shelter during passing showers.

The exhibit features live displays of everything from leaf-cutter ant colonies (with transparent tube systems showing the ants' remarkable organized behavior) to giant walking stick insects, enormous beetles from South America and Southeast Asia, cockroaches, centipedes, scorpions, and tarantulas. The scale of some specimens is genuinely surprising — the giant stick insects and beetles prompt almost universal 'I didn't know bugs could get that big' reactions from kids and adults.

For children in the bug-fascinated phase — which reliably hits somewhere between ages 4 and 10 — the Insectarium is the most exciting building in the zoo. The density of active, visible specimens means there's always something moving, and the interpretive content is age-appropriate and well-designed for self-directed exploration.

A free-flight butterfly section inside the building allows butterflies to move through the space freely, with visitors occasionally receiving landings. It's a smaller-scale version of the dedicated Butterfly House in Chesterfield, but a pleasant bonus for a zoo visit.

For kids who are nervous about bugs, the glass-case format of most displays means full close-up viewing without any contact risk. The building is well-supervised and staff are knowledgeable and enthusiastic about answering questions.