Tortrix moth caterpillars
Two species of tortrix moth caterpillars are often found in gardens and indoors where they bind leaves together with silky threads they can also damage fruits
Scientific name Cacoecimorpha pronubana and Epiphyas postvittana
Plants affected Many edible and ornamental plants both indoors and outdoors
Main symptoms Caterpillars feed within leaves bound together with silken threads
Most active April to September but all year round in glasshouses
What are tortrix moth caterpillars?
These small green caterpillars are the larval stage of moths belonging to a family called tortrix moths (Tortricidae). There are almost 400 species of tortrix moth in Britain, several species can be found in gardens, most causing no serious damage to plants, and so should be treated as part of the biodiversity a healthy garden supports. Two species can however, can feed on a wide range of plants and the leaf rolling and defoliation they cause in gardens and glasshouses often gets noticed; the carnation tortrix moth (Cacoecimorpha pronubana) and light brown apple moth (Epiphyas postvittana).
A gallery of adult tortrix moths found in Britain can be found at UKmoths
Check susceptible plants frequently so action can be taken before a damaging population has developed. When choosing management options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section and avoiding pesticides. Within pesticides the shorter persistence products (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action. Pesticide treatments are likely to kill natural enemies and are only likely to be successful if the entire plant can be reached.
- Some damage can be tolerated without adverse effects on plant health. Populations of caterpillars, as butterflies and moths are an important part of the garden ecosystem
- Light populations can be managed by squeezing the bound leaves to crush the concealed caterpillars and pupae
- Encourage predators and other natural enemies in the garden such as birds, wasps and ground beetles
- Carnation tortrix and light brown apple moths can be monitored and may be kept in check by using pheromone traps. These consist of an open-sided cardboard box with a sticky sheet in its base. A pellet which releases a pheromone is placed on the sheet; this is the same chemical produced by females to attract males. In a confined space, such as a glasshouse, the traps may capture enough males to reduce the mating success of the females. These traps are available from some suppliers of biological controls
The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.If treating then early treatment is best since young caterpillars are more susceptible than the older larva.
- Organic sprays, such as natural pyrethrum (e.g. Bug Clear Ultra 2, Neudorff Bug Free Bug and Larvae Killer), can give some control of tortrix moth caterpillars. These pesticides have a very short persistence and so may require reapplication to keep caterpillar numbers in check
- More persistent contact-action insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer, Provanto Sprayday Greenfly Killer) and cypermethrin (e.g. Py Bug Killer).
- A systemic containing the active ingredient Flupyradifurone (Provanto Smart Bug Killer) is available for use on ornamentals and selected edibles
- The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also available
Follow label instructions when using pesticides. On edible plants make sure the food plant is listed on the label and follow instructions on maximum number of applications, spray interval and harvest interval. Plants in flower should not be sprayed due to the danger to bees and other pollinating insects. Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener.
Pesticides for gardeners (pdf document)
Out of doors light brown apple moth has two overlapping generations during the spring and summer. Eggs are laid in batches on the leaves of host plants and hatch after about ten days. The caterpillars then feed with foliage sown together with silken threads and pupae where they have been feeding. In glasshouses and on houseplants the lifecycle can vary, with adults and caterpillars active from late winter until late autumn.
Carnation tortrix moth has a similar lifecycle to light brown apple moth but can breed continuously in glasshouses and on houseplants.
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.