Praying mantises
Also known as Mantids, Mantises, Mantodea, Orchid mantis
In short
Mantises are large ambush predators with spiked, folded front legs that catch any insect they can hold. They are fascinating to find but give little real pest control, because they eat bees, butterflies and hoverflies as readily as pests. Status depends on what you want: harmless to plants and people, but not a pest solution.
How it looks
Adults are elongated, about 5–12 cm (2–5 inches) in common garden species, though some species are far smaller, green, brown or yellowish, with a triangular head that swivels almost 180°, large bulging eyes and enlarged front legs held up in front of the body. Many are camouflaged as leaves, bark or, in the orchid mantises of Malaysia, flowers. Nymphs look like small, wingless adults; very young nymphs of some species mimic ants. Eggs are laid in an ootheca: a frothy mass up to about 38 mm that hardens into a brown, papery case attached to twigs, stems or walls.
Signs
A motionless insect waiting on foliage or flowers; papery egg cases on stems; remains of bees or butterflies below a flower.
Life cycle
Egg case, nymphs that moult roughly five to ten times, and adults. Temperate species have one generation a year and overwinter as eggs.
What favours it
Mantises follow flying prey, so they are often found in flowering plants that attract pollinators.
Prevention
- There is nothing to prevent; leave them be or move one gently if it is hunting at your bee-visited flowers.
- Do not rely on mantises or bought egg cases for pest control.
Treatment
Start with the first step and move down only if the problem persists.
- No control needed. If a mantis turns up on a plant you are treating for pests, move it before spraying.
- Deal with the actual pest using the IPM steps: inspect, remove by hand or water, then targeted, short-residual products following the product label.
Pros and cons
Pros
- Eat a range of insects including flies, beetles and caterpillars.
- Harmless to plants and do not damage leaves.
- Engaging for children and a sign of a lively garden.
Cons
- Indiscriminate: they catch bees, butterflies, hoverflies and other beneficial insects, and one another.
- Each mantis eats relatively few insects and they do not multiply fast when pests increase, so their pest-control value is negligible.
- Bought egg cases give no reliable pest control.
Look-alikes
- Stick insects
- Stick insects are plant-eaters with slender front legs that are not folded or spiked.
- Assassin bugs
- Smaller, with a curved beak under the head instead of chewing jaws, and front legs that are not held folded up.
- Grasshoppers
- Grasshoppers have big jumping hind legs and chew leaves; mantises have grasping front legs and a mobile triangular head.
Where you find it
Outdoor flowering shrubs, herbs and vegetables; occasionally balcony plants.
Related
Sources
Written in our own words from these sources. Check a product label before using any treatment.