What is a budworm? You will know the damage when you see it. If your buds and blooms are full of holes, you have been visited by budworms. These critters can damage a whole lot of blooms in a short time so it is important to learn a little more about them and how we can rid our roses of them.
The budworms that attack our roses are actually called tobacco budworms or Heliothis virescens. They overwinter in the south, but they can spread as far north as New England during the summer. Adult budworms are moths that are tan or brown in color with three darker stripes across their wings and they are about 1 inch in length. The eggs are deposited on, in, or under the buds and blooms and they take 2-3 days to hatch. Once they emerge they eat their way through as many blooms as they can. When they have had their fill they make their way down into the soil where they go through their pupal stage to emerge as moths about 22 days later. Warm temperatures speed up some of these processes. Now that we know what they are, let's take a look at some control measures.
Cut Your Blooms - Since the adult moths use buds and terminal growth to lay their eggs, everytime you cut your roses you are removing a possible incubation site. It is also important to remove "blind shoots" as they can also be a good incubation spot.
Keep Spraying - Although it is difficult to get spray to the budworms inside the bud, it is important to keep spraying. If they emerge from the bud and eat the tissue that has been sprayed you will have one less adult moth in your garden. Bacillus Thuringiensis or Bt as found in products such as "Thuricide" from Hi Yield is a great biological control that works on caterpillars including budworms.
Help the Good Guys - There are many insects and spiders that feed on budworms. Avoiding broad spectrum insecticides such as Sevin will help keep the beneficial insects in your garden. It is also a great idea to encourage birds to visit your garden because they will eat the moths and caterpillars that are causing damage to your roses.
Budworms can be difficult to control but by following good gardening practices and encouraging nature to give you a hand, you can keep them from turning every rose in your garden into swiss cheese. Your buds are for you to enjoy, not for the budworms.