Monarch Butterfly Predators
Millions of Monarch Butterflies become food for various predators every year. Besides their life cycle being very short, especially in the warmer months, their fragile wings are very susceptible to water. Even a few drops of the morning dew can be hazardous, and in colder weather wing icing (like aircraft) can be disastrous!
There are a multitude of little predators that eat the Monarch eggs and larvae such as ants, mites, spiders, and wasps. The adult monarchs are especially vulnerable to being eaten by predators while at the winter migratory sites where their population density is incredibly large, and the over-wintering time cooler weather causes them to be in a semi-dormant state making them easy to catch prey. Often their roosting trees are smothered with thousands of Monarchs.
The food source for the monarch larvae caterpillars is the milkweed plant. The plant contains toxic chemicals which the young monarch is immune to, and the residue of these toxins remain in the adult Monarch Butterfly.
They display bright orange and black colors to warn others of their noxious taste, which limits many hungry species. But other killers, notably mice, voles, and a few species of birds, are not deterred. The biggest threat from Monarch Butterfly predators is from two bird species: the Black Headed Grosbeak, and the Black Backed Oriole. These birds, apparently unaffected by the butterfly’s defensive chemical composition, often eat over ten percent of the monarch population in the over-wintering settlements. You can imagine a hungry bird going to the “all you can eat” buffet.