Issues with strawberry root beetles: shield your berries

One of the hallmarks of spring is the inviting taste of fresh strawberries. However, strawberries can suffer from a few pest problems, including susceptibility to the strawberry root weevil.

Weevils are insects that belong to the beetle family. There are three different types of weevils with larvae that feed on the roots of strawberry plants: the black vine weevil (Otiorhynchus sulcatus), the rough strawberry root weevil (O. rugosostriatus), and the strawberry root weevil (O. ovatus). . Since strawberries are perennial plants that go through a dormant phase in winter, their roots become a good food source for weevil larvae in winter and spring. Damaged roots can lead to a period of stunted plant growth or kill the strawberry plant completely.

If you're growing strawberries hydroponically, or if you're buying from nurseries in the spring, you probably don't have to worry about strawberry root beetle infestations. Note, however, that these weevils affect not only strawberries, but also some woody ornamental plants and other berries such as raspberries and blackberries. The methods for controlling them described in this article would also apply to these other plants.

Good products for combating strawberry root beetles:

Root Weevil overview

Strawberry root beetle larvae can damage your berry plants. Source: Lentil Cartridge

The black weevil, rough strawberry beetle, and strawberry beetle are common pests of strawberries grown in Europe and North America. These three types of weevils are very difficult to distinguish at the larval stage when they are small white maggots with brown heads. Adult strawberry root beetles and black weevils are about 8-10 mm long with red-brown or dark-brown to black bodies. Strawberry root beetles also have distinctive "curved" antennae with a bend in the middle. The black weevil is the largest of the three species. Weevils can be confused with ticks, but weevils have three pairs of legs while ticks have four.

Life cycle of the strawberry root beetle

Weevils have one generation per year. Adult weevils cannot fly and lay tufts of eggs on or just below the surface of the soil from June to September. The black weevil and strawberry root beetle reproduce asexually, which means that all of these weevils are female and can lay eggs. Weevils hibernate during their larval stage and feed on the roots of host plants such as strawberries when temperatures allow. The larvae pupate in late spring and become adult beetles in early summer to restart this life cycle.

Common living spaces

Like many other pests, adult weevils are active at night. Often found at the base of the plant or in the ground during the day, they climb plants to feed on leaves after sunset. If you suspect you may have a weevil problem, check your plants with a flashlight at night.

Weevils can also be found as random intruders in homes from June to August. They are not harmful to people or pets, and do not consume food anywhere in the home. If you find weevils in there, sweep or vacuum them up to dispose of.

What do weevils eat?

There are thousands of species of weevil, commonly named for their common host plant. As the name suggests, the strawberry root weevil and the rough strawberry root weevil feed on strawberry plants. The black weevils, on the other hand, feed on over 150 different plant species, including strawberries. Weevils form very distinctive chewing patterns on the edge of leaves and petals. While adults feed on leaves or flowers, weevils, as larvae that feed on plant roots, cause the greatest damage.

How to control strawberry root beetle

Close up of the adult weevilA close-up image of a strawberry root beetle. Source: AMagill

Controlling pests begins with understanding their behavior and life cycle. As part of an integrated pest control strategy, the goal should not be to completely remove all weevils from the garden, but rather to control their population and minimize their damage.

Organic or chemical control

Adult strawberry root beetles and black weevils can be controlled with several types of pyrethroid insecticides. However, bees are very sensitive to these insecticides, including those approved for biological use. Only spray at night and when there is no wind. Adult weevils do not all appear at the same time. If you plan to use chemicals to control their population, you may need to make multiple applications. Follow the directions on the product carefully.

Environmental control

One way to fight strawberry root beetles is to plant strawberries as annuals. You can also use crop rotation on strawberry beds with non-host crops such as lettuce to reduce the overall population of weevils in the soil.

Beneficial nematodes have also been shown to be effective against weevils. In particular, Heterorhabditis spp. and Steinernema spp. are parasitic nematodes that feed on beetle larvae. Apply the nematodes near the roots of the host plant in summer and water the area thoroughly. Maintaining a good level of moisture prevents the nematodes from drying out and increases their effectiveness against weevil larvae.

Prevent weevils

Since weevil larvae infest the roots of plants, it can be difficult to identify this pest problem until next spring, when you see poor growth. Monitoring adult weevils in the summer may give you a better idea of ​​the pest population. Examine the leaves of your plants and go outside with a flashlight to look for feeding females. You can also set up a cardboard trap near your plants, which will give these weevils an attractive habitat. Hand remove any weevils if you find them on leaves and dispose of your cardboard trap. Once you've confirmed that there is a weevil in your yard, you can also use the control methods outlined above.

frequently asked Questions

Otiorhynchus rugosostriatusThe rough strawberry root beetle Otiorhynchus rugosostriatus. Source: J. Maughn

Q: How can I naturally get rid of weevils in my garden?

A: You can use a combination of methods such as: B. Plant strawberries annually, rotate your harvest, and handpick every weevil you see.

Q: Can weevils infest your home?

A: Yes, weevils can infest your home. While they can be a nuisance, they won't transmit disease or bite people and pets. Sweep or vacuum the weevils and make sure your home is properly sealed around the foundation, windows and doors.

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