Q: I read your article regarding ladybugs and have a similar problem in a building I maintain. You suggest that Dursban or Sevin can be sprayed around door openings for control. I am curious why our exterminator contractor has told us that ladybugs are not controllable with residual chemicals because of their body structure and they do not “groom” their legs.

A: I don’t know why your exterminator thinks grooming is necessary. Most insecticides can be efficiently absorbed through the feet of insects. They don’t need to groom themselves in order to be poisoned. Dr. Beverly Sparks, Extension service entomologist, says that porous surfaces like brick won’t hold the poison as for long as sealed surfaces would. Insecticides also vary in the amount of time they remain chemically active. Read the label of the product you choose to determine how often it should be resprayed.