Identify, prevent and combat carrot flies

The carrot fly, also known as the carrot fly, can severely damage the delicious carrot roots and also affects other umbellifers. You can find out how you can prevent the carrot fly from us.

The carrot fly (Psila rosae) can lead to severe yield losses in the vegetable patch, especially with carrots (Daucus carota subsp. sativus). In this article you can find out when the pest occurs and how it can be combated or avoided.

Carrot fly: profile and way of life

The first generation of the carrot fly hatches at the end of April from the overwintered pupae in last year's carrot beds. The slender flies have reddish heads, black bodies and orange legs. After mating, the females go in search of suitable host plants. All umbellifers (Apiaceae) can be infested, so in addition to the carrot there are also

parsnip (Pastinaca sativa), celery (Apium graveolens), fennel (Foeniculum vulgare) dill (Anethum graveolens), chervil (Anthriscus cerefolium) and Parsely (Petroselinum crispum) endangered.

The 5 to 6 mm large insects are relatively poor fliers, only covering about 100 m per day. The flight time of the carrot fly extends over several days to weeks. Therefore, it takes around mid-May for the carrot flies to find the young carrots. A female lays up to 100 eggs in 4 weeks of her life. The carrot fly runs down the carrot plant to the root neck and lays its eggs in cracks in the ground around the root.

The creamy white larvae of the carrot fly, up to 8 mm in size, migrate into the ground after hatching and feed on the young fine roots. The feeding damage caused by the first generation is usually still minor, but can lead to the death of the plants in germinating crops or in young carrots. The larvae pupate, hatch and, a few weeks later, lay the next carrot fly eggs in the ground. The second generation of carrot flies hatches from July and, more rarely, a third generation in early autumn. Only these populations start eating the carrot itself and thus cause the typical damage caused by the carrot fly. The brownish to black feeding tunnels of the larvae can be seen in the middle to lower part of the root. The carrots can then only be partially used in the kitchen. The feeding tunnels are also later used by other pathogens as entry points, which can lead to root rot or storage rot.

Tip: If the feeding passages are more visible in the upper part of the roots, it is probably an infestation with the carrot leaf miner (Napomyzacarotae). The whitish feeding tunnels in the carrot leaves also stand out here, which do not occur at all in the carrot fly. A similar pattern of damage appears in the case of an infestation with wireworms (Agriotes), but their feeding tunnels are usually significantly larger and reach deeper. Wireworms are also much less common on carrots than the carrot fly.

Fight carrot flies

In the meantime, pesticides that chemically combat the carrot fly are no longer permitted for home and allotment gardens. A small infestation can be controlled by plant-strengthening measures. For this purpose, there are lime-based spreading agents against carrot flies, even for biological use. These will be sent directly to planting carrots be deployed. Also azadirachtin in the form of neem oil, a natural active ingredient from the seeds of neem tree (Azadirachta indica), can help control adult carrot flies on the leaves.

Orange and yellow panels help estimate the carrot fly's flight time and intercept at least some adults before they lay eggs. Our Plantura Yellow Boards are harmless to humans and pets as they do not contain any toxic substances. Outdoors, you should only attach the yellow boards in the immediate vicinity of the carrots so that primarily pests get caught in them. They also indicate when the crop protection nets should be spread: at the latest when the first carrot flies can be seen on the yellow boards. There is no way to combat the larvae once they have spread through the stock. Therefore, prevention of an infestation is the best method of control.

How can you prevent carrot flies?

Basically, there are various ways to prevent a carrot fly infestation. When harvesting umbellifers, you should remove everything from the bed, including foliage, root debris and other crop residue. Thanks to their typical smell, these attract carrot flies and give them room to hibernate. More tips on how to proceed Harvesting and storing carrots can be found in our special article. In addition, the following points are particularly important to note:

Carrot Fly Resistant Varieties

Choosing the right type of carrot can prevent carrot fly infestation. On the one hand, early-ripening, fast-growing varieties such as 'Nantaise 2/ Milan' are suitable for this, which are harvested as early as June and are therefore not eaten by later carrot fly larvae. Tolerant and resistant varieties are also suitable and can also be sown later. They are either hardly or not at all attacked by the carrot fly. The robust hybrid varieties 'Ingot F1', 'Resistafly F1' and 'Flyaway F1' stand out here.

Crop rotation and mixed culture

Carrots and other umbellifers should not be grown back-to-back on the same plot. A break in cultivation of 4 years not only avoids the reproduction of the carrot fly, but also other important carrot diseases such as carrot blackhead (Alternaria) or Sclerotinia rot (Sclerotinia sclerotiorum). A mixed culture with bulbous plants (Allioideae) like onion (Allium cepa), Garlic (Allium sativum) or leek (Allium porrum) keeps the carrot fly away thanks to the leaf vapors. At the same time, the bulbous plants benefit because the onion fly (Delia antiqua) can't stand the smell of umbelliferae.

The location also plays a role: carrot flies are sedentary insects that only cover short distances and prefer locations where there is no wind. They can hardly spread on windy carrot stands.

Nets against carrot flies

Crop protection nets are ideal for preventing carrot fly infestation. The nets should have a mesh size of 1.35mm x 1.35mm or smaller to successfully keep the pest out. If you also want to avoid the carrot leaf miner, you should use nets with a mesh size of less than 1 mm.

These are spread out over the carrots at the beginning of May, for example over a wire framework, so that the nets do not put any pressure on the plants even when it rains. The nets should touch the ground at the edges and be fixed with stones or boards so that no carrot flies can get in there either. The nets can be removed about 3 to 4 weeks before harvest, as an infestation would only affect the fine roots, but would not cause any damage to the roots themselves.

plant pathogens roundworms (Nematoda) can also cause damage to carrots and many other crops and should be avoided through good crop rotation and mixed cultivation. We give tips on how to recognize and combat a nematode infestation.