The Black Vine Weevils -Their Life Cycle & the Damages Done By Them

The Black Vine Weevils – Their Life Cycle and the Damages Done By Them

As the gardening season approaches, all the gardeners are worried about bugs and insects attacking their gardens and ruining the beauty of their garden by eating up the stems, leaves and even roots of the plants. One such threatening bug is the black vine weevil. They are one of the most troublesome pests for the gardens and landscape spoiling plants, eating up buds and killing the plants. The amount of damage done by the black vine weevil is devastating. They attack more than hundreds of varieties of unusual plants that include rhododendrons, yews, azaleas as well as hemlocks. They are even harmful to a variety of indoor plant such as ferns, begonias as well as other potted plants.  But, the most favorite plants for this black vine weevil is the cyclamens, and they are often known as the cyclamen grub too. So, let us have a look at what are black vine weevil and why they are harmful.

Black vine weevil is one of the most dangerous pests for the nurseries as well as for the landscape plantings. They are believed to be native of Europe and were reported for the first time in 1910 in Connecticut. It is one of the most destructive pest as well as the most distributed species around the world of the Otiorhynchus genus. The choice of food for the adult are Taxus spp, Rhododendron spp., yew, euonymus, Euonymus spp., Ilex crenata and Japanese holly while the larvae feed on roots of the hemlock and Tsuga spp. More than 100 species of this insect has been identified.

1. How to spot a black vine weevil?

Spot Black Vine Weevils

The appearance of the larvae of the black vine weevils is white, and they are legless with C-like shape and a brown head. The adults are black to slate gray, flightless and around 9-13mm in length and do have a short snout along with an elbowed antenna. The front wings of these insects are covered with small concave areas and have small patches of golden hair around its body. The strawberry root weevil looks identical to the black vine weevil but differs regarding size. The strawberry root weevil is only half the size of the black vine weevil.

The adult black vine weevil feeds during the night while causing damage to the plants by eating up the edges of the leaves. During the day, they hide in the crack, soil, mulch and the debris. The larvae are the one that causes the maximum amount of damage to the plants. These grubs create a tunnel through the roots of the plants as they keep feeding. Due to this, the plants get wilted and later on dies despite watering them regularly. The larvae griddle the first stem which is just under the soil line. This is the primary reason why you should keep an eye out for the infestation of the Black vine weevil in your garden.

The adult black vine weevil destroys the plants by munching on the broad leaves of the evergreen plants as well as other hoists which consists peripheral notching of the greeneries.  For detecting an infestation of the black vine weevil at the earliest stage, investigate at the center of the plant right at the middle of the plant which is close to main stems of the plant.  It is the main place where the black vine weevil would attack at the earliest stage. Look out for chewed cut-off and notched leaves which indicate that the harmful pests were feasting on the leaves overnight. The night is there only feeding time, and when they are detected and disturbed, these little insect drops themselves to the ground and use their coloration to stay undetected. Their coloration helps them to camouflage with the color of the ground. There only female black vein weevil as they don’t need a male partner to conceive. They produce their eggs without mating. In rare cases, the adult grubs have caused damage to the plants as they only feed on the stem and the leaves of the plants. The main damages are caused by the adult grubs which feasts on the root of the plants leaving them hollow which causes obstruction to the supply of nutrients to the rest of the part of the plant. Eventually, due to the lack of supply of water and nutrients, the plants die.

2. How harmful are they?

weevils harmful

The Black vine is one of the dangerous pests that could infest your garden, and you definitely don’t want them as they will leave your whole garden damaged and lifeless. The most harmful are the larvae of the grubs as they eat their way through the roots of the plant leaving them hollow which disrupts the flow of water and nutrients of the plants and the plants ends up dying. The adult hides under the fallen leaves as well as between cracks and under the soil. The grubs or the adult black vine weevils hide inside the soils, debris or between the crack and other areas where they would get shelter and protection during the winter.

After rain or wet summer, the adult gets abundant and can be seen in and around the house getting attracted to lights. Though they don’t cause any damage to the indoors but ruins your garden. They lay their eggs at the base of the plants and they hatch into grubs within ten days after the eggs are laid. After the eggs are hatched, the grub starts feeding on the roots of the plants and has the capability to destroy a plant fully. The most common reason for the infestation of these pests is due to the purchasing of infested plants. While purchasing a plant, make sure that they aren’t infected. The most common sign of noticing it would be to see the leaves. If there is a sign of adult feeding on the leaves, then there is a maximum possibility that the adult has laid eggs in the root ball of the plant. Since the larvae usually leave deep down in the root ball, they can’t be reached with the help of pesticides.


The nourishing development stage amid grown-up advancement offers a long window of chance to endeavor to break the dark vine weevil life cycle. Bug sprays connected to foliage are a very much acknowledged technique for lessening the grown-up populace. Materials marked for utilizing shift in various states; be that as it may, those generally utilized which have organophosphate as the primary ingredients for counterattacking the bugs. Every pesticide has its preferences and regulation. Orthene will kill grown-ups for around three days following application, whether in a few expresses this might be the main enlisted and successful bug spray, and it has low mammalian poisonous quality. Furadan (carbofuran) is very compelling against the adult bugs; anyway, it is likewise profoundly harmful to warm-blooded animals. The pyrethroids must be connected at their most elevated marked rates to accomplish control; and still, at the end of the day, the detoxification instrument in grown-up weevils is disturbing. A typical perception with these pyrethroids is that grown-ups are “thumped down,”to recuperate at least one day after the fact. To get the best impact from any foliar treatment, splashes ought to be coordinated roughly two hours after dusk to boost coordinate contact of weevils with shower beads as they feed. Moreover, splashes ought to be planned to kill overwintering grown-up weevils, with follow-up showers booked roughly at regular intervals (contingent upon temperature) to wipe out gatherings of grown-ups following their development and before laying any eggs. One bug spray that has been dismissed for use against dark vine weevil grown-ups is the sodium alumni-o-fluoride. This mineral has the detriment in being rough to showering hardware, and in having high application rates that outcome in exceptionally noticeable deposits on foliage. Notwithstanding, the material itself has low danger to warm-blooded animals, is acknowledged by natural producers, and is particularly viable against biting creepy crawlies, even those, (for example, Colorado potato scarab) that have turned out to be impervious to most different bug sprays. Control of dark vine weevil grown-ups generally started with the use of draws bound with lead arsenate. Late work by Ocean Spray Cranberry recommends that the utilization of draws with more present day bug sprays, for instance, cryolite can be a compelling method to control grown-ups. The upsides of utilizing communicate goads would be that disturbance of different bugs, (for example, parasites) coming about because of foliar splashes can be evaded, a little amount of bug spray would be required on a for each section of the land premise, and straightforward mechanical gear can be utilized to apply these items. I foresee that noteworthy changes responsible for dark vine weevils will be proficient by joining more current stomach-acting bug sprays, for instance, pyrroles or microbial poisons with snares. The definition of draws could itself be a functioning territory to investigating. Apple pomade or grain-based draws are 60-year-old advances, which could conceivably be enhanced by a comprehension of attractants and phagostimulants affecting dark vine weevil conduct.

Observing grown-up action is important to be sure that grown-ups are available and to time showers legitimately. A few checking techniques have been considered, every merit for particular circumstances. Four general classes of systems are utilized to screen grown-ups:

  • Confirmation of sustaining action,
  • coordinate checks,
  • Utilization of human-made refugee, and,
  • Entanglement traps.

3. Methods to check out black vine weevils

One of the easiest checking strategies is to search for the indents in leaf edges normal for root weevil encouraging. The drawbacks of this strategy are that there is no real way to figure out which of the numerous types of root weevil caused the sustaining, and it is hard to tell when the encouraging occurred, and other physical harm, for example, wind whip or katydid nourishing, can look like root weevil bolstering. Dark vine weevils feed most strongly amongst development and the commencement of egg laying. This nourishing decreases amid egg laying movement until the point when sustaining stops and the grown-ups search out overwintering locales. In this way, a steady can’t be characterized that relates the include of new sustaining indents leaves to the number of dynamic grown-ups, and the absence of bolstering in the harvest time can give a misguided feeling that all is well and good that adults are missing. A standout amongst other approaches to utilize perceptions of sustaining indents is to decide if weevils are available or missing in particular regions inside nurseries. Certain plants, particularly weedy Epilobium spp. are an exceptionally favored grown-up sustenance contrasted and Rhododendron spp. Subsequently, Epilobium can be utilized as marker plants: they will be nourished upon (and grown-ups can be found amid the day under these plants) sometime before any indents are found on Rhododendron. Coordinate tallies of grown-up weevils is a troublesome checking technique on the grounds that these bugs are dynamic during the evening and are likewise subtle. Compass net testing is, for the most part, unsuccessful, be that as it may, holder developed plants can be shaken over a sheet to acquire the sustaining grown-ups. The best time to utilize this procedure is from two or three hours from dusk until midnight. Grown-up weevils search out spots to stow away amid the day; this conduct can be utilized to trap them in human-made refugia. Burlap sacks can be used as trunk wraps, and are valuable for single or multi-stem plants. Influence 4-to inch the long way accordion overlays in the burlap pack, at that point hold one end against the base of the storage compartment, and freely winding the wrap. Try not to attach the burlap to the storage compartment since this strategy requires grown-up weevils to move into the openings in the vertical folds. Totally caught weevils, loosen up the burlap and shake it over a white sheet or solid clearing. Rehashed and successive expulsion of the grown-ups could be adequate for stifling the weevil populace in little private plantings.

black vineweevils in compartment

Another strategy is to put a board on the ground with the goal that it contacts the base of the storage compartment. Trap sheets can, yet don’t get the same number of the creepy crawlies in light of the fact that they don’t encompass the storage compartment. Likewise, grown-ups may cover up under leaves or another duff instead of under the trap load up. In nurseries, particularly with compartment developed plants, entanglement traps are a powerful grown-up observing technique. Entanglement traps work by catching slithering creatures in a despondency from which they can’t get away. A straightforward entanglement trap can be made by setting a 4-inch measurement plastic glass in the ground with the goal that the edge is at or just underneath the dirt surface. Coat the upper edge within the glass with a 2-inch band of slick grease, which keeps the caught creepy crawlies from leaving. To keep the trap from topping off with water system water or rain, I reverse a 1-gallon pot over the trap, in the wake of having first cut three legs into what initially was the edge of the pot. Primer outcomes from catching grown-ups in a business azalea nursery recommend that entanglement trap gets are expanded when put close to within a right-edge curve of a prohibition hindrance. Insects are meeting a sharp-calculated obstacle might be compelled to turn, thus improving the probability of falling into the entanglement trap. Dark vine weevil is a standout amongst the most undermining nuisances for the nurseries and in addition for the scene plantings. They are accepted to be local of Europe and were accounted for without precedent for 1910 in Connecticut. It is a standout amongst the most ruinous bug and in addition the most disseminated species around the globe of the Otiorhynchus family. The decision of nourishment for the grown-up is Taxus spp, Rhododendron spp., yew, euonymus, Euonymus spp., Ilex crenata and Japanese holly while the hatchlings sustain on foundations of the hemlock and Tsuga spp. In excess of 100 types of this creepy crawly has been recognized. Son now that you know what black vine weevil is and why they are harmful let us have a look at the life cycle of this pests.

4. The life cycle of black vine weevil

life cycle of the black vine weevils

During the life cycle of black vine weevil, it mostly spends its days inside the soil living around the roots of its host plants. During the spring, it changes itself to pupae and comes up as an adult. Then, around a couple or more weeks, they start to deposit their eggs near to the crown of the hosting plants. At the start of the ten-day, the larvae started to burrow into the soil and began feeding on a cycle of a generation every year. The adults overwinter and which in turn complicates their life cycle and since the eggs are laid earlier. The adult remains open to threats while the larvae are safe as they mostly remain under the soil.

So, if you are looking for a healthy garden, make sure that it is free of pests such as the black vine weevil which would destroy your garden. While the adult will be feasting on the leaves, the larvae would be eating up the roots. Do a regular checkup of your garden and if there is any sign infestation, step in the earliest stage and do the needed.

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