Accurate identification of Desert locust imagos

Accurate identification of Desert locust imagos should be based on the following criteria :

General morphology

 Size : males are 60-75 mm long, females are 70-90 mm long.

Overall body colour

In the solitarious phase, adults are pale yellow, grey or beige. In the older forms, only mature males show a slight yellowing of the hind wings. Solitary hoppers are usually green or brown, without any black.

In the gregarious phase, adults undergo considerable colour changes as they age. Immature juveniles are an overall pinkish colour. When immaturity is prolonged (imaginal quiescence) due to unsuitable breeding conditions (shortage of rainfall and/or inadequately low temperatures), imagos become progressively dark red or brown. This phenomenon is noted in quiescent populations of the Mediterranean region under cold weather conditions.

Sexual maturity begins when ecological conditions become suitable for breeding. Locusts then gradually turn a highly characteristic bright yellow. For a certain period of time, locust populations can be composed of a mixture of red and yellow locusts.

Gregarious hoppers are typically yellow and black. The extent of blackness (maculation) depends on the degree of gregarisation of the locust. Transiens forms, midway between solitarious and gregarious, show little maculation, whereas type gregarious populations are heavily maculated.

Shape of male cerci

Square, which is highly characteristic and distinguishes them from Anacridium spp., whose cerci are cone-shaped and pointed at the ends.

Wing colour

Transparent, pale yellow, pinkish or reddish. No brown or blackish spots or crescents.

Prosternal tubercle

Visible, located on the ventral side between bases of the forelegs ; this feature is noted in the Desert locust, the Red locust and the Tree locust  it is missing in the Migratory locust and the Senegalese grasshopper.

Desert locust hoppers can be easily confused with those of Anacridium spp. which have many highly characteristic small white tubercles on the hind part of the pronotum. Solitarious hoppers are generally green without any black spots in all stages of their development. Brown hoppers are observed but not as commonly. Gregarious hoppers are yellow with black maculation.

The  Desert Locusts can produce 2 to 3 generations yearly with a facultative developmental arrest in the adult state in dry periods during which time the locusts remain immature and breeding activity is sometimes stalled for several months. Females lay eggs 2 - 3 times in their lives, at most about 100 eggs for solitary females and 60 for gregarious females. The incubation period is around 10 days to 2 months depending on temperature and soil humidity. Overall, one solitary Desert Locust generation lasts 2 - 6 months.

 Male and female may be identified on the basis of the tip of the abdomen, the female have hard dark hooks