The praying mantis, with its distinctive forelegs, is a common and fascinating sight in gardens. These insects are often found camouflaged among leaves and stems, leading many gardeners to wonder if they pose a threat to plant health. This article clarifies the true role of the mantis in the ecosystem by exploring its predatory nature and specific diet.
Are Praying Mantises Herbivores?
Praying mantises pose no danger to plants because they are obligate carnivores, meaning they must consume other animals to survive. They do not possess the mouthparts necessary to chew through leaves, roots, or fruit, and they gain no nutrition from vegetation. When a mantis rests on a flower or branch, it uses the foliage for camouflage and to stage an attack. Their feeding method involves ambush predation, waiting perfectly still for unsuspecting prey to wander within striking distance.
The Specifics of the Mantis Diet
The diet of a praying mantis changes as the insect grows from a tiny nymph to a full-sized adult. Newly hatched nymphs focus on consuming small, soft-bodied insects such as aphids, fruit flies, and leafhoppers. As they mature, their size allows them to tackle a broader menu of garden inhabitants, including crickets, grasshoppers, moths, and various beetle species. The mantis is a generalist predator, consuming almost any moving creature it can successfully capture. This lack of discrimination means mantises will also attack beneficial insects, including honeybees, butterflies, and ladybugs. They are also highly cannibalistic, with larger individuals frequently consuming smaller mantises when prey is scarce.
How Mantises Function as Biological Control
The predatory nature of the mantis makes it a natural biological control agent, helping to regulate pest populations without the need for chemical intervention. Their hunting strategy relies on stealth and raptorial forelegs equipped with sharp spines to grasp and immobilize prey. This sit-and-wait approach allows them to patrol a specific garden area, clearing out passing insects. They are effective at controlling large pests like grasshoppers and caterpillars that can quickly damage crops.
However, mantises are not a complete solution for pest management due to their low population density. A small number of mantises cannot eradicate major infestations of fast-breeding pests like spider mites or large aphid colonies. Unlike specialist predators, the mantis does not target a single pest species; it provides generalized suppression of the insect population. While their large size allows them to take down formidable targets, this must be balanced against their tendency to consume pollinators and other garden allies. Gardeners use them as a supplemental layer of defense alongside more targeted pest management strategies.
Encouraging Mantis Populations in Your Garden
Gardeners wishing to capitalize on the mantis’s predatory skills should focus on creating a welcoming habitat. The first step is avoiding broad-spectrum chemical pesticides, which kill mantises along with their food source. Providing dense, layered vegetation is helpful, as mantises prefer to hide and ambush from thick shrubbery or tall grasses. Plants in the rose and raspberry families, along with native flowers, attract the smaller insects that serve as their primary food source.
Many gardeners introduce mantises by purchasing egg cases, known as oothecae, which can be affixed to plant stems or branches. Each ootheca contains hundreds of eggs that hatch in the spring once temperatures warm consistently. When purchasing oothecae, it is important to verify the species. Non-native species like the Chinese mantis can grow quite large and may prey on beneficial native insects and even small vertebrates. Maintaining a healthy, diverse ecosystem with varied plant life and a shallow water source will naturally encourage mantises to stay and hunt.