I am not locust specialist Sir, just trying to helping you. Did you try different temperatures and bugdorm / metal cage? is it desert locust? check out following references;

Dudley, B., Gregory, G., & Payne, D. (1962). An all-metal cage for rearing locusts in the laboratory. Bulletin of Entomological Research, 53(2), 219-221. doi:10.1017/S0007485300048082

Hunter-Jones, P. (1956). Instructions for rearing and breeding locusts in the laboratory.—9 pp. London, Anti-Locust Res. Cent.Google Scholar

Hunter-Jones, P. (1961). Bearing and breeding locusts in the laboratory.—[2nd edn.] 12 pp. London, Anti-Locust Res. Cent.Google Scholar

thanks Dear, I shall check these

Because it's not their natural place do do so I believe.

True, try to follow these guidelines. Many thanks Vimal Kumar sahib

I don't think so Vimal Kumar Semwal , It just needs bit of troubleshooting. Because I know some labs in UK have established colonies of desert locust. It means locusts can be reared in the lab. Also from ecological and behavioral perspective, insects rarely deviate from their natural phenomenon under artificial conditions provided that they are under ideal environmental conditions and individuals are healthy (having proper diet).

Farrukh Baig try to contact the UK lab you mentioned and get the protocol from them. May be they have mentioned it in some of their publications.

First of all, I assume that you are rearing desert locusts. Can you confirm? If so, then those cages are not ideal. I prefer wire mesh cages with one side of plexiglass that can be shifted up and down to facilitate refreshing their food. By the way, how long have to waited for mating to happen? Have the adults already turned yellow? If not, you should wait a bit longer.