Better known as ‘stick insects’ or ‘leaf insects’, phasmids appear in different shapes, sizes and colors which allows these insects to camouflage themselves amongst the leaves and the branches that they live in. Phasmids inhabit the warm parts of the world and are considered nocturnal creatures because they become active mainly during the night. Most phasmids are relatively larger than most other insects while some phasmids can even grow up to 30 cm in length. Experts believe that there are around 2500 species of phasmids recognized around the world, while around 150 species can be seen in continents such as Australia. This article will describe briefly the appearance, life cycle, camouflaging tactics and food habits of phasmids in order to understand how they cope with the challenges of nature.
-Appearance of phasmids
As mentioned above, phasmids appear in many sizes and shapes and most of these shapes mimic the natural habitat the creatures are expected to live in. Thus, leaf like flattened appearances and cylindrical or stick-like elongated appearances are the two predominant appearances seen among this group of insects. Phasmids have three pairs of legs, while most of them have two pairs of wings. The front wings, which are useful to protect the much fragile and larger hind wings, are short and stiff. The hind wings are the ones that aid the insects to fly, although most phasmids cannot fly or only can glide for short distances. In general, phasmids are slow movers and prefer to lie motionless rather than resorting to flying when their lives are threatened. The undersurfaces of the phasmid wings are usually bright in color and it is not visible until the phasmids spread their wings during flying. When considering the male and female phasmids, the males appear smaller than the females although the former posses a larger wingspan than their female counterpart. Phasmids may also have two antennas, which can often grow up to several centimeters long along with compound eyes similar in nature to most other insects.
Female phasmids lay around 100 to 1000 eggs over 2 to 3 seasons and during lying down of eggs, the phasmids may just drop the eggs on the ground or else flick the eggs to the ground in order to spread them wide. Once hatched, the nymphs that emerge will climb on to a plant and will undergo several cycles of shedding of its skins before taking the adult form. At the same time, the nymph form does not contain wings as does its adult form.
The appearance itself is one form of camouflaging used by the phasmids while change of color to that of the surrounding branches and leaves is another tactic. When threatened, phasmids can remain motionless and fall onto the ground with the wings and the feet hidden in the body as if it is a ‘stick’. At the same time, the bright colored undersurfaces of the wings can also be used to scare away predators. A rhythmic swinging movement, as if it is a leaf, is also being used by phasmids to distract its predators. In addition, phasmids also have the ability to grow back their feet if in case they have to shed one of them as a means of distraction.
Phasmids feed on leaves of trees and shrubs that they live in. However, only the adult forms can feed on the mature leaves, while the nymphs will only feed on younger and softer leaves. Some species of phasmids can also feed on grass as well.