The proverbial worm in the apple is the larva of a butterfly, the codling moth (lat. Laspeyresia pomonella). The dreaded pest spreads quickly and threatens to destroy entire crops. Fortunately, the moth and its voracious offspring can be easily controlled with biological measures.

The codling moth caterpillars like to eat apples

Table of Contents

Show all
  1. the essentials in brief
  2. damage picture
  3. combat
  4. prevention
  5. Look
  6. occurrence and distribution
  7. life cycle
  8. harmful effect
  9. frequently asked Questions
  10. What is the confusion technique and how does it help against the codling moth?
  11. Can Neem also fight codling moth?
  12. Are there effective home remedies for codling moth?

    13. The shiniest apple contains the biggest worm.

    the essentials in brief

    • An infestation of the codling moth can be recognized by the small boreholes in the apple
    • The codling moth can be effectively controlled with pheromone traps, nematodes or the granulosis virus
    • Beneficial insects such as parasitic wasps, bugs or earwigs reduce the number of codling moths

    damage picture

    A codling moth infestation is easy to recognize by the boreholes, just a few millimeters in size, that the larvae eat into the tender skin of the unripe fruit. Typically, it eats its way in a spiral from the outside in to the core, which is also affected. Feeding passages and cores are contaminated with brown piles of excrement, both of which are clearly visible when the apples are cut. Apples that are attacked early usually fall off early.

    What can you do effectively against the codling moth?

    In the case of an acute or imminent infestation with the codling moth, biological or natural control methods are recommended, since chemical sprays also threaten the harvest - after all, these are toxins that you would later eat with the apples. In addition, many insecticides are generally not approved for use in home and hobby gardens.

    pheromone traps

    Pheromone traps are less suitable for controlling the codling moth directly, but give a very good impression of the actual infestation. In addition, you catch the male moths, which as a result can no longer fertilize the eggs of the female animals - ergo no offspring hatch either.

    Pheromones are sex attractants that are spread into a sticky trap coated with glue. The male butterflies confuse the scent with that of the females, stick and can then be collected. And this is how the system works:

    • time: one trap per fruit tree from the beginning of May
    • control: treatment measures are required from five butterflies per week
    • Further measures: immediate injection with granulosis viruses

    By the way, you can ask your local plant protection office when the codling moths start laying their eggs.

    granulosis virus

    However, the time window for treatment with granulosis virus preparations such as Madex is very narrow, since you have to catch the newly hatched fruit maggots on their way to the apple. This hike only lasts a few days, which is why it is so important to precisely control the flight times using a pheromone trap. The flight peak is usually between mid-May and mid-June, which is why treatment with this biological agent also takes place at this time.

    Granulose viruses are effective against codling moths, but are harmless to bees and other beneficial insects - not unimportant in fruit growing, after all, these insects are supposed to fertilize the apple blossoms. And this is how the preparations are used:

    1. Mix the preparation exactly according to the package instructions.
    2. Pour it into a clean garden sprayer.
    3. Carefully spray the whole tree with it.
    4. Do not leave untreated corners, as the caterpillars must absorb the active ingredient directly.
    5. Repeat the application three times at intervals of eight days.
    6. Also, repeat them from late July/early August to intercept the second generation.

    Apply the treatment on a dry day when it is neither raining nor windy. Both have a negative impact on the result.

    nematodes

    Steinernema feltiae nematodes have also proven to be effective against overwintering codling moth larvae. These are tiny roundworms that invade the larvae and kill them with a bacterial infection. And this is how the method works:

    1. Nematodes are sprayed after harvest.
    2. They should reduce the infestation pressure in the coming year.
    3. Damp weather (drizzle) and temperatures above eight degrees Celsius are ideal.
    4. Do not spray on sunny days, preferably in the evening
    5. Nematodes are very sensitive to UV light
    6. spray all winter hiding places: trunk and branches, stakes and sticks, fruit mummies)

    This is how you prevent an infestation by the codling moth

    As is so often the case, the worst infestation can be prevented by taking targeted preventive measures. The basis for success is knowledge of the life cycle and biology of the codling moth in order to know when the time is right.

    encourage predators

    One of the most important preventive measures is to encourage beneficial insects and birds, because they like to eat the codling moth - and many other pests. Make your garden bird-friendly, for example by putting up (cat-proof!) nesting boxes, feeding stations in winter and a bird bath in summer. Sparrows, various species of tit, blackbirds and other songbirds will be happy to settle down with you.

    In the case of insects, these species in particular are effective predators of the codling moth:

    • catchy tunes
    • bugs
    • parasitic wasps

    Ichneumon wasps kill codling moths

    In particular, the parasitic wasps of the species Elodia tragic, Ascogaster quadridentatus and Trichogramma enecator have proven to be good means of control. They are available from specialist retailers. The beneficial insects attach to small cards that you simply hang between the branches of the apple tree. This should be done as early as possible in the year so that the pressure of infestation does not become so great in the first place.

    Minimize hibernation sites

    In particular, the bark of older apple trees offers the codling moth perfect hiding places in winter. Therefore, you should treat them preventively:

    • scrape off bark: In late winter (January / February) work the bark of the apple trees with a stiff brush or a special metal bark scraper. Loosen the loose pieces of bark, but don't damage the bark.
    • Corrugated cardboard lanyard: From the end of June, wrap a strip of corrugated cardboard 10 to 20 centimeters wide around the trunk and fasten it securely. The caterpillars crawl underneath to pupate and are easy to collect.
    • Falling on support posts: You should also attach the same rings to any support posts that may be present. Check the corrugated cardboard traps weekly and remove them completely from the end of September.
    • Remove rotten support posts: Rotten support posts are also often used for hibernation and should therefore be removed in autumn

    Unlike the winter moth, however, glue rings have no effect on the codling moth and are therefore not a viable method of prevention or control. Instead, you can try this age-old hack, which also has other benefits:

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    collect larvae

    Between January and April, check the trunks of your apple trees regularly for overwintering codling moth larvae or their pupae. Shake the trees, because the animals fall to the ground and can be collected. Infested fruits should be removed as early as possible during the growing season to prevent further development of the fruit maggots.

    Appearance of the codling moth

    The adult moth is very small with a length of only one centimeter and also has an inconspicuous coloration. The gray colored cover wings (front wings) have wavy, dark transverse lines, and there is also a red-brown spot on the outer edge that is characteristic of the species. The slightly shiny hind wings are colored grey-brown in one colour. Externally, male and female animals hardly differ from each other.

    From the whitish, only about one millimeter large, individually deposited eggs hatch initially up to two millimeters long, whitish caterpillars. These change their appearance as they develop and are later pink and up to two centimeters long. The dark warts and the dark brown head and neck shield are also typical of older caterpillars. The brown pupa, on the other hand, is also quite small at around eight to ten millimeters in length.

    Similar looking pests

    In order for countermeasures to be successful, the type of pest on the apple tree must be known. There are some species that are quite similar to the codling moth in terms of appearance and/or damage. However, some of these are fought with other means and/or at other times than this one. In the following table you will find an overview with clear distinguishing features.

    kind Latin designation characteristics damage picture Distinctive features to the codling moth
    plum moth Laspeyresia funebrana grey-brown moth with a wingspan of up to 15 mm, caterpillar up to 15 mm long and pink to bright red bluish discolouration of the fruit, traces of feeding, gummy flow copper-brown spot on the forewings, codling moth penetrates to the core
    peach shoots Lapeyresia molesta dark moths with a wingspan of up to 16 mm, caterpillars up to 14 mm long, whitish to reddish with a brown head capsule Feed marks, gum flow on infested fruit copper-brown spot on the forewings, codling moth penetrates to the core
    Little fruit moths Grapholita lobarzewskii moths up to 8 mm long with yellow-brown forewings and grey-brown hind wings, caterpillars up to 12 mm long, yellow-grey to light pink in colour Entry and exit holes in the fruit, with a furrow, sometimes caused by leaf miners no faecal deposits in the fruit, does not penetrate into the core
    sorrel sawfly Ametastegia glabrata Larvae are green and have seven pairs of legs uses apples for pupation no droppings in the holes, typical web
    apple sawfly Hoplocampa testudinea white-yellow larva with ten pairs of legs clear signs of wear up to the cavity Damage often up to the size of a walnut, infested fruit falling off

    occurrence and distribution

    The codling moth prefers to eat apples, but not only

    The codling moth - sometimes also referred to as the apple moth - threatens the fruit tree harvest almost all over the world. The species primarily affects apple trees, but it also affects pears, quinces, peaches and even walnuts. Depending on the region and thus the climate, the pest goes through up to two generations a year and thus multiplies very quickly.

    This is typical for the Lake Constance region, for example, but the codling moth is also appearing earlier and more frequently in other parts of Germany. This is related to the increasingly warmer temperatures in spring and summer, which create ideal living conditions for the moth to develop. For example, the flight time has been pushed forward significantly, as spring begins earlier and earlier with mild temperatures.

    Life Cycle and Biology

    The larva of the codling moth - which is also often referred to as the fruit maggot - overwinters under the bark of the apple tree, where it is embedded in a tight web. As soon as the temperatures are warm enough, usually from the end of April, the caterpillars pupate and hatch as adult moths from mid-May.

    Only a little later, the female animals lay their 20 to 80 eggs in the still young fruits. Another two weeks later, the first larvae hatch and go to the food source: the animals feed on the peel, the pulp and the core of the apple - the latter is a clear indication of a codling moth infestation, since the larvae of other pests don't do this.

    After another three to four weeks, the caterpillars have eaten enough and go to the trunk of the apple tree to spin themselves in the bark and spend the winter there. The growth of the codling moth larvae is strongly dependent on the temperature: If it is colder than ten degrees Celsius, the eggs and larvae do not develop. However, after a warm spring and summer, two or even three generations of the pest develop and cause huge damage.

    harmful effect

    The codling moth prefers for egg laying and nursery - of course - apple trees of different varieties. However, the species can also be found on other types of fruit, especially in regions with a warmer climate. The following are particularly at risk:

    • apricots
    • pears
    • chestnuts
    • cherries
    • peaches
    • plums
    • quinces
    • walnut
    • hawthorn

    If the weather conditions in one year are so favorable that the population and thus the infestation increase by leaps and bounds, this strong proliferation continues over the next few years. During and after a warm, dry year, preventive and control measures must therefore be carried out with particular care.

    tips

    Fruits that are infected early usually have to be sorted out, while those that are infected late can often be used at least partially. In this case, generously cut away the damaged areas in the apple. However, these fruits can no longer be stored.

    frequently asked Questions

    What is the confusion technique and how does it help against the codling moth?

    The previously mentioned pheromone traps serve to confuse the situation. Although these are well suited to anticipating the peak of the codling moth flight and thus the right time for spraying, they only have a minor influence on the population and thus the infestation pressure.

    Can Neem also fight codling moth?

    While neem is effective against many fruit pests, it is not effective against codling moth.

    Are there effective home remedies for codling moth?

    Instead, you can use wormwood manure as a proven home remedy. To do this, pour ten liters of water over 300 grams of fresh wormwood leaves and leave the mixture to ferment in a plastic container for ten to fourteen days. Only fermented wormwood slurry is effective against the codling moth, but a simple infusion is not strong enough. You can stir in a handful of rock flour (€14.13) to counteract the strong smell. The spraying with wormwood must be carried out in the spring between mid-May and mid-June and preferably repeated several times.

    tips

    For the wormwood manure, use dried herbs collected the previous year instead of fresh leaves. After all, you will hardly find suitable wormwood herb this early in the year.

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