Roses are favourite flowers in any garden, despite the fact that they have a reputation for being fussy and difficult to take care of. Roses are highly susceptible to both disease and pests. This requires special attention such as regular spraying with pesticides and herbicides. Common rose bugs include aphids, Japanese beetles, thrips, cane borers, rose scale, rose leaf hopper, sawflies and spittle bugs.
Aphids, or Macrosiphum rosae, are 1/16 to 1/8 inch long insects; they are also called plant lice. The insects are usually light to lime green but are often brown, black, or red. Aphids feed on new growth and soft tissues and suck the juices causing leaves to curl and die. The insects excrete a sticky honeydew like substance which attracts ants and becomes home to fungus and mildew. Aphids overwinter in the form of tiny black eggs on rose stems near new leaf buds. Infestations can be removed with a hard spray of water. Promoting insect predation of aphid easing insects like lacewings, ladybirds and syrphid fly larvae is the best non-chemical way to control aphids.
Thrips or Anaphothrips obscures are also known as grass thrips and oat bugs. The dark brown insects have fringed wing tips and are less than 1cm in length. Thrips are very quick moving and feed on the flowers that are on the verge of blooming. The damage they cause keep the flowers from blooming and when the flowers do open they are distorted with brown, yellow, white or black spots and lines. Treatment is to the remove all infected bugs from the bushes and garden. Nurturing beetles, ladybirds and lacewings are a good natural defence against thrips. Adding beneficial nematodes to the soil in spring is also recommended.
Rose Leaf Hopper
Rose leaf hoppers are small yellow or green insects which feed on the underside of rose leaves creating mottled, pale, or flecked marked leaf surfaces. Full grown insects are winged and move in flying leaps. The insects are less than a cm in length and very difficult to see since they move very fast. Extensive infestations lead to premature leaf fall. Rose leaf hoppers suck on foliage juice and create yellow and brown leaves. This is referred to as hopperburn or tipburn since the damage starts at the tip of the leaves and works inward. The most effective way to deal with rose leaf hoppers is with specially formulated insecticides.