This is because butterfly caterpillars are host specific. Plant-wise, the caterpillars of some butterfly species like asters, black-eyed Susan, clover, lupines, milkweed, sedum or violets. Aspen, birch, cherry, hackberry, oak or willow trees make caterpillars of other butterfly species equally happy.
each Br-F bond would be polar or BF4-, there is an extra electron making this a polar molecule. PCl5 has the Cl atoms that must be as far apart from each other as possible and therefore would create equal but opposite pulls.ach Br-F bond would be polar or BF4-, there is an extra electron making this a polar molecule. PCl5 has the Cl atoms that must be as far apart from each other as possible and therefore would create equal but opposite pulls.
SiCl4 or silicon tetrachloride is a non-polar molecule. It is used  in a variety of ways, but mainly in the production of very pure  silicon. non-polar compound occurs when there is an equal sharing of electrons between two different atoms. Examples of household non-polar compounds include fats, oil and petrol/gasoline. Therefore (per the oil and water rule of thumb), most non-polar molecules are water insoluble (hydrophobic) at room temperature.