Solid insect growth regulating compositions

A solid insect growth regulating composition having prolonged action for exterminating and/or preventing breeding of pests in water systems comprising:

• (a) an insect growth-regulating active ingredient;
• (b) an organic substance having a solubility of not greater than 2% in water at 20.degree. C. and a melting point of 35.degree. C. to 100.degree. C., wherein the organic substance is selected from the group consisting of a saturated monohydric alcohol, a normal-chain fatty-acid, an n-alkan, an n-alkylbenzene, an alcohol ester of a fatty acid, an ethylene glycol ester, tallow, lard, palm oil, hardened rapeseed oil, hardened castor oil, hardened whale oil, beeswax, purified lanolin, vaseline, and a urethane compound having no isocyanate terminal obtained through reaction of polyoxyalkylene compounds and organic polyisocyanates;
• and
• (c) a glycol having a melting point of 35.degree. C. to 100.degree. C. selected from the group consisting of polyethylene glycol having average molecular weight of not less than 1,000, polyoxyethylene polyoxypropylene glycol having 80% or greater of the ethylene oxide weight in the molecule thereof and average molecular weight of not less than 1,000 in the propylene oxide moiety, polyoxyethylene polyoxybutylene glycol having 80% or greater of the ethylene oxide weight in the molecule thereof and average molecular weight of not less than 1,000 in the butylene oxide moiety, and polyoxyethylene polyoxypropylene polyoxybutylene glycol having 80% or greater of the ethylene oxide weight in the molecule thereof and the average molecular weight of not less than 1,000 in the butylene oxide moiety or propylene oxide moiety,
• wherein (i) the weight of constituent (b) is equal to or greater than 3% based on the total weight of said solid insect growth regulating composition, (ii) the sum of the weights of constituent (b) and constituent (c) ranges from 20% to 98% based on the total weight of said solid insect growth regulating composition, and (iii) constituent (b) and constituent (c) are added in molten form and then cooled to form a solid during the manufacturing process of said solid insect growth regulating composition.