An example of the bush-cricket Polysarcus denticauda outbreak from Vráble area (SW Slovakia, DFS 7775) in 1947. You can see characteristic melanistic coloration of gregarious form in sampled specimens. For details see TV document (minutes 18:08-18:50).
All pictures from the archive of STV
Such plague years of this bush-cricket were described in Austria in 1947-1948 (Watzl 1948), in Slovakia by Gulička (1954), which remembered observations of Ferianc from May 1932-1934, when the White storks Ciconia ciconia (31.5.1932, ca 300 ind.) consumed huge amounts of P. denticauda between Rimavská Sobota and Rimavské Janovce (S Slovakia DFS 7686) (Ferianc 1965). Gulička (1954) mentioned P. denticauda outbreak also from June 1946 in the same site in area of Rimavská Sobota. More about the current status of species populations in Slovakia you can find in Krištín & Kaňuch (2009) and Krištín et al. (2009).