1-(6-Chloronicotinyl)-2-nitroimino-imidazolidine (common name: imidacloprid) and related imidazolidine compounds control effectively hemiptera and other sucking insects, but their activity level against lepidoptera species is not high enough for practical use. In the search for compounds acting with different insecticidal spectrum from that of imidacloprid, we found the title thiazolidine derivative 3-(6-Chloronicotinyl)-2-nitromethylene-thiazolidine (2). Quite recently, we communicated on the enormous enhancement of the insecticidal potential of 2-nitromethylene- and 2-nitroimino-imidazolidine by chloronicotinylation of a ring nitrogen atom, and this beneficial effect was also observed in the transformation of thiazolidine (1) to compound 2, which controlled the green rice leafhopper (Nephotettix cincticeps) in a low dose of 0.32 ppm (LC90). More notably, compound 2 exhibited high activity against typical lepidoptera species such as the tobacco cutworm (Spodoptera litura), diamond-back moth (Plutella xylostella), and rice leafroller (Cnaphalocrocis medinalis) with LC90 values of 1.6, 1.6, and 8 ppm, respectively. In contrast, imidacloprid (7), its nitromethylene derivative (8), and the lead compound (9) showed only modest activity against these lepidoptera species. Among over one thousand compounds of this class we have prepared so far, compound 2 is the only one that showed sufficient efficacy against lepidoptera. The corresponding nitroimino thiazolidine and nitromethylene pyrrolidine derivatives (3 and 4) showed only slight activity against lepidoptera species, while the isoelectronic oxazolidine (5) was inactive. Interestingly, 3-(6-chloronicotinyl)-2-nitroimino-3(H)-thiazole (6) bearing a C=C bond in the ring had a comparably high level of activity against hemiptera species to imidacloprid, but no appreciable activity against lepidoptera. Compound 2 was prepared as described in Scheme 1.