D E S E R T  L O C U S T  B U L L E T I N Glossary of terms The following special terms are used in the Desert Locust Bulletin when reporting locusts: Non-gregarious adults and hoppers   isolated (few)   very few present and no mutual reaction occurring; 0 - 1 adult per 400 m foot transect (or less than 25 per ha). scattered (some, low numbers)   enough present for mutual reaction to be possible but no ground or basking groups seen; 1 - 20 adults per 400 m foot transect (or 25 - 500 per ha). group   forming ground or basking groups; more than 20 adults per 400 m foot transect (or more than 500 per ha). Adult swarm and hopper band sizes very small   swarm: less than 1 km2 band: 1 - 25 m2 small   swarm: 1 - 10 km2 band: 25 - 2,500 m2 medium   swarm: 10 - 100 km2 band: 2,500 m2 - 10 ha large   swarm: 100 - 500 km2 band: 10 - 50 ha very large   swarm: 500+ km2 band: 50+ ha Rainfall light 1 - 20 mm moderate 21 - 50 mm heavy more than 50 mm Other reporting terms breeding the process of reproduction from copulation to fledging. summer rains and breeding July - September/October winter rains and breeding October - January/February spring rains and breeding February - June/July decline a period characterised by breeding failure and/or successful control leading to the dissociation of swarming populations and the onset of recessions; can be regional or major. outbreak a marked increase in locust numbers due to concentration, multiplication and gregarisation which, unless checked, can lead to the formation of hopper bands and swarms. plague a period of one or more years of widespread and heavy infestations, the majority of which occur as bands or swarms. A major plague exists when two or more regions are affected simultaneously. recession period without widespread and heavy infestations by swarms. remission period of deep recession marked by the complete absence of gregarious populations. upsurge a period following a recession marked initially by a very large increase in locust numbers and contemporaneous outbreaks followed by the production of two or more successive seasons of transient-to-gregarious breeding in complimentary seasonal breeding areas in the same or neighbouring Desert Locust regions.