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The proverbial worm in the apple is one of the most common apple pests. But thanks to various strategies to combat the codling moth, you are not powerless against it.
From the beginning of spring, the codling moth (Cydia pomonella) is up to mischief and the feeding passages of its larvae can quickly spoil the fun of growing your own apples. This article explains how to recognize the codling moth by its damage. In addition, important ways of controlling the codling moth are summarized below.
By the way: The codling moth is sometimes confused with the codling moth. However, the codling moth does not form a web, which is why the distinction is easy.
Detect codling moth: appearance and damage
Codling moth damage can be recognized by the feeding holes of the larvae in the fruit, which are also called worm bites. If you cut open the fruit, you can see the typical feeding passages, which are also contaminated with small black particles of faeces. If the apples are attacked at an early stage, the unripe fruit will fall off and rot. If the infestation sets in later in the year, the apples can still be used. The affected areas must be cut away. In addition, the shelf life of the apples is reduced.
Codling moth pheromone traps enable particularly early detection. The pheromones attract male codling moths, which then stick to the sticky trap. In this way, the flight of the moth and thus the early laying of eggs can be recognized.
At a glance: What does the codling moth look like?
- Adult moths: Grey-brown wings with light stripes and copper spots on wingtips; length about 1 cm; wingspan about 2 cm; mainly active at dusk.
- Eggs: Oval, shiny shields.
- Codling moth larvae: White-yellowish with a dark head; initially 2 mm in size, fully grown up to 2 cm.
- Codling moth Damage: Small black drill holes in the apples; Contamination of the feeding passages and the entry point withmealy feces.
If you want to fight the codling moth, you first have to recognize it: the codling moth is a brown-grey butterfly that often has two generations per year in our country. The adult animals are grey-brown moths with a wingspan of around 2 cm. The wings are streaked with light-colored stripes and end with a copper-colored spot at the tip. In the spring, the first generation of adult moths hatch. After laying eggs, the larval stage and pupation, the second generation follows in July. The small butterflies are particularly active at dusk when the temperature is below 20 °C.
Codling moth eggs can be recognized by their oval, shiny and shield-like shape. The codling moth females deposit these on the fruit and leaves of the apple trees shortly after hatching.
The larvae of the codling moth are initially 2 mm long after hatching and white-yellowish with a dark head. They seek out their food source and burrow into the flesh of the apples. Three to four weeks later, the caterpillars, which have grown significantly, leave the apples again and migrate to the trunk. There they pupate. Depending on the season, the codling moth larvae, which are now up to 2 cm in size, develop into adult butterflies. Otherwise they hide under the bark to hibernate protected.
Fighting codling moth
There are a variety of different approaches to controlling the codling moth. The most relevant are briefly presented here. The growth and development of the codling moth are strongly dependent on temperature, which makes it difficult to determine the appropriate time to combat it.
The first moth generation hatches between mid-April and early May. The second moth generation appears from July.
Tip: codling moth trap to monitor moth flight: Traps are used between mid-April and early May and from July to August. Codling moth traps do not manage to combat the pests, but they can be used to determine the moth flight and thus the mating period. Yellow panels or specific pheromone traps are used. Pheromone traps are clearly preferable to yellow boards: They only attract codling moths. This facilitates the evaluation. In addition, this prevents completely harmless insects from getting on theAdhesive surfaces of the yellow boards die. The time of treatment can be determined by the flight of the moth, because after the eggs are laid it takes 7 - 15 days for the first larvae to hatch. During this time window, the apples should be checked regularly and then treated.
Fighting codling moth with pesticides
Chemical codling moth sprays are not permitted for hobby gardeners and their use is not advisable due to the many biological codling moth control methods. Approved biological codling moth sprays are preparations based on granulosis viruses. But in the meantime, resistance has already developed: some codling moth maggots remain unimpressed by the biological agent. The granulosis virus preparations are only effective on young larvae, so timing and multiple treatments are important.
Nematodes against codling moth
Nematodes can also be used to control codling moths, as they represent a biological and harmless type of treatment. This not only protects people and the environment, but also protects other animals, insects and plants. Our Plantura SF nematodes, for example, are very good against codling moths, but can also be used against fungus gnats or ants. The tiny roundworms of the species Steinernema feltiae parasitize the larvae of the codling moth and thus prevent further reproduction. The larvae often choose dry places in the cracked trunk of apple trees as winter quarters. Therefore, a suspension containing the nematodes can be sprayed on the trunks of apple trees from September to March. The ideal weather conditions for spraying are cloudy, humid and temperatures above 12 °C, because nematodes are sensitive to UV radiation, drying out and low temperatures. Since the larvae remain in the same place throughout the winter, the extended treatment period is another advantage of this method.
Tip: Nematodes are a large and diverse family. Our SF nematodes are specialized for only a few hosts, so they pose no threat to humans, animals, or other plants.
parasitic wasps against codling moth
Certain parasitic wasps also help against codling moths, as they parasitize the pests' eggs. Here it is worth attaching the imcommercially available small cards. This is best done from April or May.
Fighting codling moth with home remedies
Even without spending a lot of money, you can achieve success in controlling codling moths. For example, you can mix a spray against codling moth based on wormwood yourself. To prepare the wormwood slurry, about 300 g of fresh wormwood leaves must be added to 10 liters of water. Then let the whole thing stand for about 14 days, stirring it occasionally. In the next step, the leaves are strained and the manure can be used as a codling moth spray.
Fixing 10 to 20 cm high rings of corrugated cardboard around the trunk of the apple trees is also relatively easy and cheap. Since codling moth larvae like to visit the cardboard to pupate, it is worth attaching from June onwards. Now all you have to do is check the cardboard rings regularly and remove the larvae if necessary.
Using glue rings, on the other hand, does not usually help with codling moths.
At a glance: how to fight codling moth?
- Pay attention to the right time to fight, since many types of control only affect a certain stage of development.
- Common and approved codling moth sprays are based on granulosis viruses. However, these only affect newly hatched larvae.
- Codling moth nematodes are an effective control method. They parasitize the larvae of the codling moth.
- Certain species of parasitic wasps parasitize codling moth eggs.
- Various home remedies such as wormwood manure or corrugated cardboard can also be part of the control strategy.
Prevention of codling moth
Infestation with codling moths cannot usually be completely prevented, but there are a number of preventive and damage-reducing measures.
- If you keep shaking your trees off in winter, most of the pupated larvae will fall off. Ideally, place a large foil or tarpaulin under the tree, which will make it easier to collect the larvae afterwards.
- You can also remove larvae by searching and brushing the trunks - especially older trees.
- Remove infected fruit immediately. In this way you can prevent the larvae in your apples from developing into adult moths.
- Foster beneficial insects,such as earwigs and birds, which are natural enemies of codling moths. You can find tips on this in our article on bird-friendly gardens, among others.
Codling moths are unfortunately not the only pests that spoil our apple harvest. Learn more about other diseases, pests, and treatment tips with our Apple Tree Diseases article.