Otiorhynchusspp.
As I chock up through bright - leaved hydrangeas that were taller than I was , I come boldness to face with a industrial plant covered in leaves notched with half - lunation chew crisscross .
I dove in , inspecting the foliation for clew about who had cause the damage .
Aha ! A utter mallet rolled off a leafage as I rustled through , and landed on the priming coat . I took a photo and travel on , convert this was a random attack by a now dead mallet , and I did n’t have to concern about a pest outbreak in the hydrangeas .
Adult weevil damage.
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Later though , while doing some inquiry , I realise I ’d been play a trick on by that mallet . It was playing dead .
fortify with some cognition about this strange puppet , I hit the muckle from the works and scouted the soil , finding pockets of round white eggs around the roots .
Thanks to that adult beetle ’s obvious eating harm , I ’d unearth an emerging root weevil problem .
Causing both modest cosmetic and more terrible damage to a wide ambit of legion , tooth root weevils are common – and if you know what you are looking for , they are gentle to identify .
So read on to find out how to key these insects , and discover the control options useable to you !
Here ’s what we ’ll cut across in this templet :
What You’ll Learn
What Are Root Weevils?
Also known as honker beetles , thanks to their farsighted elephant trunk - similar “ noses , ” root weevil are part of the Curculionidae family in the mallet order Coleoptera .
Both the adult and the larvae may damage a wide-cut variety of host , from evergreens to deciduous and herbaceous plants , and food crops as well .
The adults manducate ragged D - shaped notch out of the folio edge , and the larvae feed on the roots . grownup harm is cosmetic , but too many chewing adults can result in thin new growth .
The real reason we are talking about root weevils here , though , is because of the larvae that care to hide in the soil .
These grubs give on root hairsbreadth , larger etymon , and plant summit , causing reduced vigor , world-wide plant greensickness ( yellowing ) that wo n’t react to watering or fertiliser , dieback , girdling , and in some cases , death .
seedling , newfangled works , and potted industrial plant are most susceptible .
Identification
Besides some size differences , the different uncouth garden weevil species look quite similar to each other in each of their leg of life history .
The adults are brown or inglorious , with backbreaking elytra ( extension covering ) that are speckle with indentation . The elytra are fused together , so these beetles ca n’t fly .
Their distinctive snouts and elbowed antennae make them leisurely to severalize apart from other mallet .
The ball are orotund , and one millimeter in diameter . They start out white and eventually turn dark-brown .
The larvae are slightly C - shaped , white to drub color in legless grubswith wan orange - browned nous . They range in size of it from a quarter to a one-half inch in distance .
The pupa are blanched , and if you determine them in the soil , they will have the beginnings of grownup features such as legs tucked underneath them .
Many of the common garden species are from theOtiorhynchusgenus , including the contraband vine weevil ( BVW),O. sulcatus , which will snack on over 200 species of industrial plant includingyews , hemlock , rhododendrons , euonymus , astilbe , Funka , andpeonies .
This species is one of the larger type in the family , with the gloomy colored adults reaching three quarters of an in , and larvae up to half an column inch in distance .
The cryptic browned strawberry root weevil , O. ovatus , lovesstrawberries , boo , dahlias , and more . The adult are only about a quarter of an column inch long , so these are quite a bit littler than the BVW .
The rough hemangioma simplex root weevil , O. rugostriatus , will feed onroses , strawberries , hiss , gooseberries , andcotoneasterbushes , and solid ground between the BVW and strawberry rootle weevil in size , at about four - tenth of an inch long . The adult are clay colour and , as their name intimate , the elytra are deep indented .
Lilac stem weevil , O. meridionalis , are shiny calamitous and about a third of an inch in length . These feed on ornamental such as lilac , peony , privet , and euonymus .
Biology and Life Cycle
The life cycle is similar across the usual metal money , with some variations depending on the climate .
Most weevils procreate asexually and never produce males . In fact , BVW Male have never been seen .
female person lay upwards of 300 eggs in soil cracks , starting midsummer and through evenfall . If you have a potted plant that you ’ve seen adults on , absent the pot and you may find minuscule groups of ball laid in pockets on the edge of the root ball against the mountain , and throughout the soil .
The nut hatch about 10 days after being put down , and the larvae move to the roots to feed during what ’s known as the first eating period .
The larvae overwinter in the dirt . In the spring , they continue feed and produce during their second feeding period , which is the most destructive .
After pupating , the adults emerge in mid to recent outpouring , and will feed for two weeks to a month before begin to place eggs . This is known as the pre - oviposition degree .
Adults are slow moving , ca n’t take flight , and do n’t move far . They will play utter when disturbed . They are nocturnal , and become more active bulge about an hour after sunset .
In mild climate , you may see active weevils or larvae class round , and the life sentence rhythm is shifted . The adult come forth in tardy summertime rather than in outpouring , and they may be dynamic through the winter months and other bounce as well .
Root weevil make out one generation per class .
Monitoring
Fortunately , these pestilence make supervise gentle for us .
The alimentation wrong done by adults is very noticeable , and since the adults do n’t move far or fast , you may assume they have or will soon lie egg in the soil near the roots of the plant life they are flow on .
set about keep an eye out for fresh leaf notches in the give , and supervise your plants throughout the season .
Scout for grownup on a cloudy day , or at night when they are combat-ready .
Dig up a suspect flora or two to search the antecedent and wall stain for ball or larvae . The larvae are most well noticed in the fall or early bounce , when they are full grown .
Organic Control Methods
go about these pestilence with anintegrated pest management ( IPM ) strategy , combining monitoring with ethnical and biological methods for safe , effectual control .
When attempting ascendance of these pests , the best alternative is to focus on the larvae . The adults do not jaunt far , so killing the larva will pass to eventual obliteration of the population .
Cultural and Physical Control
establish plants with lots of root biomass are much more tolerant of root weevil feeding than fresh novel seedlings and new industrial plant .
start out with intelligent plant , and choose resistant cultivars if they are available .
Since these insect ca n’t wing , they are circulate via infested plants , soil , and debris . Inspect all incoming plants . withdraw and dispose of crop junk .
Go through your plant at nighttime , handpicking or dislodging the beetles into a bucket .
Set up pitfall traps by sinking cups into the dirt , so the cupful mouth is even with the ground surface . Partially fill them with a mixture of body of water and easy lay .
you may choose to cover the traps with a curve tile , or fabricate a little roof of some form to keep rain and irrigation pee out .
Keep in psyche these trap are not selective for beetle !
On trees and shrubs , use masking tape measure slathered in a gluey material on the lower trunks and stems , to get the adults as they creep up to prey in the eve .
Stiky Stuff is a recommended ware that’savailable from Arbico Organics .
Stiky Stuff
Cultivate the stain in April to endanger the grubs to the sunlight andhungry Bronx cheer .
Use minor grain or cereal plant ascover cropsor revolve with these , as they do n’t serve as hosts for root weevils .
Biological Control
Encourage ground foraging birds to gossip the soil around your plants , and hopefully root up some grubs , by adding a layer of tear up oak leaves underneath your plants .
One of the most efficacious treatment for root weevils is drenching nematodes into the dirt to direct the larvae and pupa . Make indisputable to note the soil temperature at the time when you want to treat , to choose the best choice .
NemaSeek Hb
UseHeterohabditis bacteriophorawhen soil temperatures are above 42 ° atomic number 9 .
These nematodes aim stationary blighter include pupa , and areavailable at Arbico Organicsin change amounts as NemaSeek Hb .
NemAttack and NemaSeek Combo Pack
Or buy NemAttack and NemaSeek Combo Pack Sc / Hb , also from Arbico Organics , which combinesSteinernema carpocapsae , a nematode which attacks participating pest like the larvae , andH. bacteriophora .
Apply nematode in mid - July to mid - September , and maintain soil wet to keep the nematodes alive .
Organic Pesticides
Several constituent pesticide options are available to home gardener to deal with these pests .
Beauveria bassianais useable in certain conceptualization as a biopesticide , such as BioCeres WP , which isavailable at Arbico Organics .
BioCeres WP
These products may be applied to foliage as a striking insecticide , and may render some control condition of the feeding adult .
AzaGuard Insect Growth Regulator
Azadirachtin acts not only as a repellant , but also works as an insect outgrowth governor . AzaGuard isavailable at Arbico Organics .
Chemical Pesticides
Pyrethroids such as esfenvalerate and fluvalinate ; neonicotinoids such as imidacloprid , clothianidin , and acetamiprid ; carbamates such as carbaryl ; and organophosphates such as malathion will kill antecedent weevil , especially adult .
However , it is hard to effectively control them in the most destructive phase , which is when they are underground , with pesticide . The honest option for that is a nematode drench as account above .
go for chemical pesticide targeting adults during the pre - oviposition stage , after hatching and before nut laying . This is a period of time of about two weeks after the first signboard of leaf notching . Apply late in the day , when the adults become active .
Young larva are more susceptible to pesticide as well , so you should time pesticide applications for grubs when they are newly hatched and feeding on the theme .
Most of these pesticides are not selective for pest insect , and they will have damaging effects onbeneficial insectsand pollinators . apply them only as a last resort , and come after software instructions cautiously .
Nosey Beetles
Since both adults and root weevils in the immature stages feed on plants , these worm are not a welcome find .
They can affect a wide-cut variety of host , meaning you are almost certain to have something growing in your garden that these chow will make out to nosh on at some point .
Nematodes are one of the best selection for controlling the larvae , and not only are they secure for good insect , they will set on a variety of other pests as well !
Plus , there is an mixture of cultural and physical controller pick available for you to try .
And for more selective information about otherpests in the garden , check out these guide next :
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Sylvia Dekker
