Abstract: The invention relates to novel N-[3-halo-4-(hexafluoropropoxy)-5-trifluoromethyl]phenyl-N'-benzoylureas of the formula ##STR1## wherein R.sub.1 is hydrogen or halogen and R.sub.2 and R.sub.3 are halogen, to a process and intermediate for the preparation of these compounds, and to compositions containing them for use in pest control, in particular for controlling insects and representatives of the order Acarina that attack plants and animals. The novel compounds exhibit in particular larvicidal activity.

Abstract: A process for the production of modified polymers, preferable in organic solvents, by radical-initiated polymerization of(Ia) 70 to 99.9 parts by weight of esters of the formulaCH.sub.2 .dbd.C(R)--COOR' (Ia)in which R is --H or --CH.sub.3 and R' are 1 to 18 C-alkyl radicals, at least 50% by weight of the esters of (Ia) being those in which R' are 1 to 4 C-alkyl radicals,(Ib) 0, 1 to 20 parts by weight of .omega.-hydroxyalkyl esters of acrylic, methacrylic, maleic and/or fumaric esters, the said dicarboxylic acids are possibly etherified on the second carboxylic group with 1 to 12 C-atoms containing alcohols and(Ic) 0 to 10 parts by weight of other unsaturated monomers, the sum of (Ia), (Ib) and (Ic) amounting to 100 parts by weight, in the presence of(II) 5 to 40 parts by weight of terminal blocked alkyl-hydrogen polysiloxanes, the alkyl radicals containing 1 to 4 carbon atoms, with a viscosity of 20 to 1000 cP at 20.degree. C.