What Kills a Butterfly?

Butterflies are flying insects that typically feature beautifully colorful wings that often frequent flower gardens. Butterflies are exposed to deadly threats like most other living things in nature. Some threats to butterflies are natural, such as predators that must eat the insects for nourishment. Other threats are caused by humans. These anthropogenic threats often effect the entire environment.

Predators

Some birds, mammals and insects actively hunt and eat butterflies. These predators include wasps, ants, birds, snakes, toads, rats, lizards, cats, monkeys and parasitic flies. Frogs and spiders are known to eat butterfly eggs and caterpillars as well as butterflies themselves. Some butterflies have developed bad tastes to deter predators. Others camouflage themselves or make themselves look like other creatures to avoid being eaten.

Pollution

Butterflies are highly susceptible to air quality. Butterflies breathe through holes called spiracles that are found along the exoskeleton of the thorax and abdomen. Butterflies living in an area of thick air pollution take toxins directly into their body. This threatens their health and can lead to their death. Also, the air pollutant ozone kills milkweed that grows on the ground. Milkweed is the sole food source for monarch butterfly caterpillars. These butterfly larvae starve without the plant.

Pesticides

Farmers and gardeners use pesticides to kill unwanted insects that eat their plants. This practice destroys destructive pests as well as nonmalignant insects, such as butterflies. Caterpillars, in particular, are threatened by pesticides. Most types of caterpillars eat leaves. Leaves that have been spread with pesticide kills any caterpillars that eat them. This means that the caterpillars won't grow into butterflies. Conscious gardening patterns help reduce butterfly fatalities. These practices include reducing pesticide use or avoiding pesticide use on plants often visited by butterflies and caterpillars.

Genetically Modified Crops

A 1999 a study published in "Nature" found that monarch butterflies were threatened by the pollen of genetically modified corn crops. The corn in this study was genetically engineered to contain a pesticide to kill invading insects. The pollen from these plants would become airborne and dust the leaves of milkweed plants that grow along corn fields. Milkweed is a main staple in monarch butterfly diets. Half of the butterflies in the study died. The other half grew to be only half of their normal size.