Browse for Bugs!

Browse for Bugs: What Plants Do Our Insects Eat?

Zoos work hard to make sure their animals are well-fed, and Butterfly Pavilion is no exception. The difference? Instead of giraffes and elephants, we have small and mighty species like leafcutter ants and butterflies. Luckily for our exhibits, Butterfly Pavilion’s horticulture staff doesn’t cut down an entire tree when a single branch will do. Even if the amounts are smaller, feeding invertebrates is still complicated. After all, there are around 400,000 different kinds of plants in the world, and millions of plant-eating insect species. How is a horticulturist to know what to grow? Some insects have a broad appetite for many kinds of plants. Our scavengers, such as cockroaches, like all sorts of plants to snack on. We grow enrichment for them, such as edible flowers, fragrant herbs, and even veggies. By adding new plant fragrances, flavors, and textures to their enclosures, we keep their environments novel and exciting. An overgrown zucchini goes a long way for these insatiable insects! But many of the plant-eating insects we showcase at Butterfly Pavilion are much pickier. These preferences aren’t arbitrary but are related to their interactions with secondary chemical compounds that plants produce to defend themselves. Different insects have different tolerances, so our zookeepers can’t just switch food plants without making sure it is part of that insect’s healthy diet. For example, our stick insects usually like to eat plants related to roses. If you’ve seen blackberries or raspberries growing in our outdoor gardens, these are our main browse crop for those insects. Sometimes, they will nibble on guava or privet leaves, but we usually offer the plants they like the most. Our new leafcutter ants (Atta mexicana) fit into both categories when it comes to choosing leaves for their fungal chambers.  Just like many humans, they really like to harvest one plant for a while and then suddenly, they reject it. This habit really keeps the horticulture team on our toes! They seem to like flowers of all kinds, as well as leaves from some of our tropical trees and shrubs, such as skyflower (Duranta erecta) and firecracker plant (Hamelia patens). Part of the fun is watching the leafcutter ants process different leaves and flowers and carry them to different parts of their habitat.  Leafcutter ants are selective and look for specific traits when they choose what leaves to harvest for their fungus. They like leaves from woody plants more than herbaceous ones, and fresh tender growth or flowers more than old leaves. They dislike plants with tough or sappy leaves. They especially avoid plants with certain compounds called terpenoids, which are found in everything from eucalyptus to citrus to cinnamon to tomatoes. It turns out that many plants have antifungal properties, which the ants certainly don’t want in their fungal chambers! These observations have led to the development of antifungal medicines for people. So how do we keep track of all the plants our animals like to eat? Our animal care team knows the preferences and specializations of each of our herbivores and lets the horticulture staff know what plants they need. They also track what gets eaten and what gets left on the plate, so that we can shift what plants we’re collecting from week to week. The horticulture team takes care of the plants without pesticides to make sure that the plant material is always fresh, tasty, and healthy for our invertebrates.  We grow almost 400 different kinds of plants at Butterfly Pavilion, including our tropical plants in Wings of the Tropics and the plants in our outdoor habitat gardens. The next time you visit, you’ll know that some of these plants are not only interesting to look at but also satisfy the appetites of our amazing animals!   

Written by Amy Yarger, Senior Director of Horticulture