Systemic insecticides, such as acephate, are only moderately effective since they do not readily penetrate the buds or the insects can infest new growth between applications. Contact insecticides, such as pyrethrins, only affect the very few adult that may be on hand during application. The most effective control has been to apply diazinon granules to the soil, along with a diazinon spray on the emerging tips every week for three weeks. This kills the adults emerging from the soil at or soon after emergence, with a follow-up kill on the bush for any adults that escaped the soil application. Midges can fly short distances, across sidewalks for example, but generally do not migrate to new sites on their own.
New infestations appear to be from pupae brought into the garden with potted roses.
Some nurseries in areas with known midge outbreaks are taking preventative measures, treating container roses with diazinon and Mavrik, to ensure their rose do not spread the midge. Since regular application of diazinon can pose a threat to stream habitats, the home gardener should consider this control only when a rose midge infestation has been identified. Rating Bad Guy. An unchecked infestation will rob a garden of bloom for the entire season, and hang around to do the same next year. And an infestation can spread to a neighbor, providing a continuing source for reinfestation.