Page Content
Identifying wingless and winged species
Background
As in all insects, the development of juvenile locusts occurs in discrete stages called instars. Juvenile locusts, no matter what their instar, are called nymphs or hoppers. Unlike insects such as butterflies, moths, bees, wasps, ants and flies, juvenile locusts exhibit what is termed “partial metamorphosis”. That is, the juvenile stages bear a superficial resemblance to the adults (see Lifecycle of a locust). (In insects such as butterflies, moths, bees, wasps, ants and flies, which exhibit “complete metamorphosis”, the juvenile stages bear no resemblance to the adults, for example, caterpillars look nothing like butterflies or moths.)
One characteristic feature of all adult insects is the presence of wings. In grasshoppers and locusts, the developing wings are referred to as “wingbuds” and are visible on the second and third segments of the thorax - called the mesothorax (middle) and metathorax, respectively. These segments lie behind the pronotum which is labelled on How to determine which growth stage a locust nymph is in). Wingbuds cannot be used for flight. The transformation of the wingbuds into functional wings for flight is only complete when a hopper reaches adulthood. The forewings (not used for flight) arise from the mesothorax and the hind wings (the flying wings) arise from the metathorax. (The middle pair of legs also arise from the mesothorax; the hind pair of legs from the metathorax.)
In some species of grasshoppers, however, the adults possess wings that resemble wingbuds of hoppers. Two such species of grasshopper include the Stripe-winged meadow grasshopper and the Wingless grasshopper (see 15. Wingless grasshopper: Phaulacridium vittatum). When wingless grasshopper species co-occur with locust and grasshopper nymphs (in particular late-instar nymphs) it can result in mis-identification of species and over-estimation of the density of populations. For example, Wingless grasshopper can be found in association with Yellow winged locust, Eastern plague locust and occasionally Australian plague locust.
Fortunately, it is relatively easy to separate adults and nymphs of these sorts of species – the pattern of venation is the key. The following images and text describe how to identify adults of wingless grasshopper species and nymphs of fully winged locust species.
The pattern of wing venation of wingless (or “brachypterous”) grasshoppers is either parallel or net-like as shown below:
Wing of an adult Stripe-winged meadow grasshopper (Brachyexarna lobipennis) - approx. 4 to 5 mm in length
The pattern of wingbud venation in nymphs of fully winged (or “macropterous”) locusts and grasshoppers is roughly fan-shaped with the veins radiating out from along the top and base of the wingbud as shown below:
