If there are worms in cherries, they are often the offspring of the cherry fruit fly. It is the most important pest that occurs on sweet cherries. The pest continues to spread as climatic conditions favor the development from larva to insect. It is, therefore, all the more important to act quickly and take preventive measures in the event of an infestation.
The life cycle of the cherry fruit fly
The insects overwinter in the soil in the pupal stage and hatch the following year between May and June to mate. Females lay one egg at a time on a ripening fruit, which is just turning yellow to yellowish-red. It takes about six to eight days for the maggot to hatch and bore into the flesh of the fruit. Here the worms live for the next three weeks, feeding on the cherries. The life cycle closes as the larvae crawl back into the soil to pupate for the next overwintering period. The extent to which a cherry tree is infested depends primarily on the weather. Thus, the severity of infestation varies from year to year. If there is a lot of rain during the insects’ flight period and low temperatures prevail, they reproduce less strongly.
Prevention instead of control
are less effective, especially on large trees, and are also detrimental to health if you still want to eat the cherries. A relatively effective control method is the application of nematodes. However, these are only 50 percent effective, so you will need to use the method more often. Nematodes live parasitically and penetrate through the larval skin to eat the pests from the inside.
- Steinernema species prove effective.
- powder with nematodes is dissolved in lukewarm water
- the tree with the solution at the beginning of June
To avoid pest infestation, proper prevention is important. The following tips will also help you if you want to control cherry fruit fly infestation. To contain the insects, you should take several measures.
If the pests have already settled in the flesh of the fruit, you should prevent infestation for subsequent years by harvesting early. This will prevent the next generation from crawling into the soil and overwintering there.
Place a tarp under the tree to make it easier to pick up the fallen sweet cherries. Leave the tarp in place for an extended period of time. This must be tight, especially at the base of the trunk. Tape it down to prevent the maggots from migrating. As an alternative to the tarp, a transparent garden fleece is also suitable so that the grass underneath still gets enough light and does not die.
Remove fruit mummies and fallen fruit
Pick overripe sweet cherries that do not fall to the ground by themselves. The larvae can descend from the fruit to the ground with a thread they have spun themselves. Fall fruit should be righted together and buried at least 20 inches deep in the ground to prevent larvae from pupating. Disposal in the compost is not recommended.
Cover the soil around the trunk with mulch in the spring. This delays the warming of the substrate, so the development of the pupae is also stalled. The flies hatch later and do not find suitable nesting sites when the cherries have already turned red. You can achieve a similar effect by not mowing the lawn under the tree until the cherry harvest.
From mid-May, when the fruit is still green, you can hang yellow boards coated with glue in the tree. The color attracts flying cherry fruit flies because they mistake the panel for ripening fruit. Often, yellow boards are coated with certain attractants that are supposed to attract insects. When they attempt to land, they stick to the surface.
Note: While this measure does not provide control, it does give a good indication of the population density of the insects. This way you can check the spread of the pests every year.
Crop protection nets
This method is very effective and is used in organic fruit growing. However, it is only recommended for smaller woody plants, as spanning large trees is no longer practical. In this case, it may help to net individual branches or to prune the tree back severely before spanning.
Planting early-maturing cherry varieties
If you don’t have a cherry tree yet but are thinking about purchasing one, go for early-maturing varieties. These woody plants come to fruit maturity before cherry fruit flies mate. They can’t find suitable egg-laying sites, so populations are automatically reduced.
Encourage natural enemies
Design your garden as close to nature as possible. In diversely structured habitats with dead wood, rock piles, and flower strips, various birds and insects find vital retreats and food sources.
- Swifts and swallows: hunt flying insects
- Ground beetles, spiders, and ichneumon wasps: larvae eat cherry fruit fly maggots
- Chickens and ducks: eat pupae from the ground
- No danger when eaten
You don’t have to worry about eating cherries with maggots. The larvae are tasteless and completely harmless to health. You will not notice by tasting whether fruit is infested or not.
Since the very idea causes repulsive feelings in many people, you can play it safe and worm the fruit:
- Pour cold water over fruit in a deep bowl
- leave for about 30 minutes
- fruit will swell and maggots will crawl out
- drain through a sieve
- repeat several times if necessary
TIP You can also deworm the fruit by hand by cutting it open and scraping out the maggots with a knife. However, this method is much more labor-intensive.