Lawn Grubs

Grub out Lawn Grubs

Lawn Grubs


 

 

 Lawn Grubs

 

 

The Problem With lawn grubs

Though many people have the motto live and let live that they apply to their daily lives, this may not be an option when it comes to lawn grubs. Lawn grubs are actually the larvae of various beetles and while a few grubs will not hurt your lawn a large infestation may cause serious damage leaving your lawn looking disease ridden with dead and wilting grass and major brown spots.


 

 Lawn Grubs

 


How Lawn Grubs Damage You Lawn

Lawn grubs damage your lawn by eating the root of you grass causing the grass to weaken and eventually die. Some types of grubs also tunnel which furthers weakens the grass and can even damage other plants as well. Worse they can bring all sorts of other unwanted pests into your yard. These pest eat the grubs and in doing so further cause damage to your grass by tunneling, or digging for the grubs that live just below the surface of the grass. Moles, raccoons, skunks, and various birds are just a lawn damaging animals that an over population of grubs can invite into your yard. So, how do you know if you have a grub problem and what do you do about it?

 

2ed54d8abcd5422 Lawn Grubs

 


Detecting A Lawn Grub Problem

Most people are not even aware they have a grub problem until late summer when their grass begins showing brown spots for no apparent reason. At this stage fighting those grubs is sometimes difficult and often results in having to replant grass in those brown spots of you lawn. Chances are if you have had grub problems in the past you have the problem again as beetles lay their eggs in certain types of soil conditions.

The best way to check for grubs is to find a sunny place in your yard and pull back a small patch of lawn. You can do this by cutting the grass in a patch with a shovel on three sides then lifting the sod. If there is a group of grubs hiding under the grass you have a problem and the only way to solve the problem is by treating your lawn and killing the grubs.

 


How and When To Treat You Lawn For Grubs

There are several kinds of chemical insecticides you can use to rid your yard of your grub problem. However, keep in mind that chemicals may harm your family, pets, and the environment. The best treatment for lawn grubs is to use organic predatory nematodes, which are a type of worm that survives in the wild and will eventually kill the grubs. Early fall is the best time to treat your lawn for grubs as the grubs are near the lawns surface still feeding. Making sure to follow the directions for the use of the nematode compound will help to ensure you are successful in your war against grubs.

 


Prevention Is Best

Of course preventing the infestation of the grubs in the first place is always the best course of action and the best way to do that is by caring for your yard properly. Avoid planting plants that are particular favorites of beetles and grubs such as baby breath will help as will keeping your lawn properly mowed. When it comes to watering deep watering periodically is better than daily misting as the grubs like moist soil. When your soil is allowed to become dry between watering it helps to make for an unfriendly environment for the grubs to survive in.   

 


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Australian Lawngrubs 4 – Argentinian Scarabs

 

645a0cc891e9b5f Australian Lawngrubs 4   Argentinian Scarabs

Argentine Scarabs, Cyclocephala signaticollis, belong to the group of white curl grubs that feed on the underground stems and roots of plants. Also known as cockchafers in some places, they live underground and cause damage to horticultural crops and turfs after African black beetle. They are most active during the months of April to June. 

It was believed that Argentine scarabs were introduced by a ship from Buenos Aires, Argentina. Native to Uruguay and Argentina, Argentine scarabs were first collected on lawns in New South Wales, Sydney during the late 1940s and has become widespread all over Sydney as far as Canberra and Parramatta in the 1950s. In the past decade, Argentine scarabs have become a serious pest for recreational turfs. 


Life Cycle 

Argentine scarabs generally have a life span of one year. They lay their eggs from early December to late January. The larvae live from early September to early October ant they grow to pre-pupa stage from mid-December to late March or early July to early November. Argentine scarabs reach their pupa stage from early September to late November. 

The adult Argentine scarab looks very similar to an African black beetle in size and shape. However, Argentine scarabs grow from 13 to 15 mm and its vulva is almost 80% of the length of the body. Furthermore, Argentine scarabs have mild tan color with thin, delicate stripes on the wing carapaces and four odontoplates in the stoma. Adult Argentine scarabs are normally seen from late November to early January. 


Field-Grown Crops 

The grubs of Argentine scarabs feed on the roots of lawns and turfs, causing the grass and other plants to weaken and die because of heat or water stress. It can be easily identified when turfs are infested with Argentine scarabs as affected plants wilt and become unstable. The grass on the lawn will soon die even if the soil has high water content; hence, they have to be treated immediately. The number of dying plants will continue to increase as the population of Argentine scarabs also multiplies. 

Argentine scarabs not only damage lawns and turfs. They also burrow into tubers, such as potatoes and kumara, which can then yield a low harvest. 


Detection 

Argentine scarabs feed on the underground stems and roots of the plants. The most destructive stage of Argentine scarabs is the late second instar and the third instar. Adult Argentine scarabs also feed on lawns and turfs although they do not cause as much damage as younger scarabs. 


It is very easy to distinguish a lawn that is swamped with Argentine scarabs. An infested lawn easily slides or rolls up like a carpet where the damage by Argentine scarabs has taken place. Moreover, destruction caused by animal feeding, such as crows, magpies, and wood duck, become obvious. 

It is best advised to leave a wet hessian bag or a piece of carpet on the lawn all night. Collect the adult Argentine scarabs the next morning before it gets hot and dispose of them. 

A pail of water mixed with biodegradable detergent can also be poured into the affected areas of the lawn. This will encourage the larvae and adult ones to move to the surface of the soil where animals can feed on them. 


Control 

Damage can be reduced by using pesticides. Apply the pesticide at dusk, when sunlight will cause the least amount of damage and the soil temperature is between 15-30°C. When using nematodes, thoroughly moisten the area to be treated before applying them and make sure that every square meter is provided with equal amount of nematodes. It is important to wash the nematodes away from the turf into the soil surface after application. 

 

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Australian Lawn Grubs 3 – African Black Beetles

 

African Black Beetles, Heteronychus Arator, are believed to have originated in Southern Africa. The presence of african black beetles in Australia was first recorded in New South Wales in 1920s. 

Usually found in Australia, african black beetles are also called black lawn beetles because they feed on lawns and grasses. African black beetles are considered as pests for non-legume crops and plants in Western Australia, Eastern Australia, Victoria and Southeast Queensland. There have been reports of attack in grapevines in McLaren and Adelaide Hills in South Australia. 

African black beetles cause significant economic damage to roots of different horticultural crops such as young rooted vines, newly-planted cuttings, olives, potato crops, and other vegetables. African black beetles also attack lawns, newly-sown pastures, young trees, and thin wooded plants. 


Life Cycle 

During spring, adult african black beetles become more active as they feed on stems and plants and lay eggs. Female african black beetles lay their eggs during spring up until the early summer. They wait for three to six weeks for the eggs to hatch into grubs. Grubs are typically white curl, C-shaped and grow up to 25 mm long. African black beetle larvae feed on organic materials and plant roots from late summer until they turn into pupae. Hence, new adults appear from mid-summer to early autumn. 

The adult african black beetle has brown to shiny black color. Its elongated, cylindrical body measures approximately 12 mm long and 5 mm wide. The rear legs are larger than the front legs. The rigid head has large, rounded and compound eyes. Usually found on the land surface or below it, adult african black beetles look like cockchafers that move slowly but have the ability to fly. Flight activities also occur during spring, although there are fewer beetles who get involved. 


Symptoms of Infestation 

The destruction caused by african black beetles normally occurs from mid-summer through winter, to early summer of the next season. New generations of adults emerge during the summer season. They feed on the trunks of young vines on the ground level or just below it. As they continue to attack, they cause wilting and collapse of the vine. Although beetle activity may be low during winter, african black beetles continue to ingest and damage the vines. 

A good indicator that african black beetles are feeding on the vine is the presence of splayed fibrous tissue on its stem. There may not be any signs of beetle feeding that can be seen above the ground until damage has progressed. Vines that have been affected by beetle feeding commonly turn red or yellow. 

Similarly, there could be african black beetles present when the grass dies in patches without any apparent reason. The root system of the lawn gets damaged and the grass looks brown or discolored. Additionally, there may also be the evidence of holes and small mounds of excavated soil due to tunnelling activities of african black beetles. 


Management and Control 

Control of african black beetles is generally difficult. October is normally the critical month for lawns. This is the season when infestation of grubs begins and female beetles start to hatch their eggs. 

Insecticides are often ineffective because adult beetles and their larvae spend much of their time under the ground. However, sprays based on chlorpyriphos or imidacloprid have been found to be an effective means of controlling african black beetles.  

Research has shown that african black beetles survive and reproduce in grassy areas, like ryegrass and paspalum. Therefore, cultivation of soil before planting as well as crop and pasture rotations help reduce the damaging effects of african black beetles. Furthermore, laying plastic mulch over elevated vine rows may control the beetles from crawling to the base of the vines. 

 

 

Japanese Beetle

 

Japanese beetle is one of the largest insect threats for plants such as strawberries, pears, peaches, raspberries, grapes, tomatoes, peppers and of course our grass. Adult Japanese beetles feed on leaves, flowers, or fruits of more than 300 plant species. 

 

Larvae of Japanese beetles have short spines and white, long brown hairs. They live in lawns and grasslands and eat the roots of the grasses and plants they infest, which damages the ability of the plants to absorb nutrients and water. During larvae stage, Japanese beetles are susceptible to a fatal disease called milky spore disease, caused by the bacteria milky spore. 

 

Asparagus, citrus fruits, plums, raspberries, and corn are some of the common host plants for adult Japanese beetles. Other plants include turf grass, walnut trees, maple trees and sassafras. They are also fond of particular weeds and non-cultivated plants such as elder, bracken, Indian mallow, poison ivy, wild grape, and smartweed. 

 

Adult Japanese beetles feed on the upper surface of the plants by chewing the leaves between the veins, which gives the leaves a skeletonized appearance. Trees that have been ruthlessly damaged by Japanese beetles looks like they have been burned by fire. Adult beetles are highly active and travels fast; thus, they can easily infest new areas from a distance of several miles. However, they only make short flights when they feed or lay eggs. 

 

 Japanese Beetle

 

Picture by James Jordan


Controlling Japanese Beetles 

In Japan, this insect is not a serious plant pest as its natural enemies control its population. On the other hand, Japanese beetles came to the United States without their natural predators. Therefore, there is no check and balance and eventually, they became a serious plant pest. Japanese beetles also found an abundant food supply and favorable climate in the United States. 

 

Japanese beetle grubs are commonly controlled using preventive soil insecticides, but there are limited options to control adults and larvae. 

 

Natural Repellents – Using natural repellents, such as catnip, chives, garlic, and dead beetles’ remains have limited effectiveness. Other organisms like nematodes and predatory bacteria are also used to control Japanese beetles. Nematodes attack adult Japanese beetles and kill them from within. 

 

When existing in small numbers, Japanese beetles can be controlled spraying simple soap-water solution. Spray the solution to the plant, shake the plant in the morning, and dispose the fallen beetles or simply pick them off attractions. Do not leave any traces of Japanese beetle on the plant as it will only attract more insects. 

 

Pesticides – There are pesticides available that are highly toxic for Japanese beetles but they produce different results. Additionally, Japanese beetles are resistant to both poison and physical damage; hence, a lot of previously successful pesticides are no longer used lately. Similarly, spraying mixture of pesticide and water with garlic cloves and hot pepper can be sprayed all around the garden to kill Japanese beetles. 

 

Net – Putting a net over strawberry and blueberry bushes can likewise control Japanese beetle attack. Beetles are not smart enough to go into the net as long as it is wide enough to go up and over and back down the other side of the plant. 

 

Traps – For a swarm of Japanese beetles limited to a small area, the beetles can be physically removed from the plant by placing traps that lure and kill beetles. However, traps can be more destructive when not properly used. Moreover, these traps lure Japanese beetles so they can also result to more and bigger infestation. 

 

Summer is the time of the year when Japanese beetles damage trees and shrubs. They feed destructively on plants like roses, crape myrtles, hops, canna, grapes, and hydrangeas. Applying a systemic insecticide is prevented in the late winter or early spring to protect plants against Japanese beetles, but at the first signs of damage, spray insecticides are utilized. 

 

 

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British Lawn Grubs

There are only two reasonable common types of lawn grubs in Britain. These are Leatherjackets and Chafer Grubs. Everybody knows the name of “Leatherjackets” but many people do not associate these lawn damaging beasties as the young of the Crane Fly or more usually “Daddy Long Legs.” Chafer grubs are the larvae of different types of Chafer Beetle, the more common being known as Maybugs or Cockchafers.

Leatherjackets

These larvae prefer damp soil and live on the roots of your grass in the lawn. You will probably see numbers of Crane Flies as Summer is starting to turn to Autumn. The adults come up from the grass, mate and the females then lay up to three hundred eggs. The eggs will hatch after two weeks or so and the grubs start to feed. Because they are small, you may not notice any damage to your lawn and as it gets colder they will go into a sort of hibernation for the winter. When Spring comes and the soil begins to get warmer, you’ve guessed it, they start feeding again. They can get to two inches in length and obviously as they get larger, they eat more. This can be the stage at which you may notice damage to your lawn. About June time they will be as big as they are going to get, they will become less of a problem and pupate. Then of course they start the cycle all over again.

Chafer Grubs

From about April to June is the time that the adult beetles emerge and start feeding on foliage flowers and available fruit. They will mate and lay eggs in batches over  several weeks. The grubs hatch out from the eggs after some four to eight weeks depending on the conditions and they start eating straight away. Just like the Leatherjackets, these grubs will quiet down over the colder winter months, resuming their feeding again in Spring. They can get to about one and a half inches in length and larger infestations can do a lot of damage to your grass. What can make the situation even worse are the things that eat the grubs digging about in your lawn to get tot this food source. In later Spring they become dormant, only to emerge as adult beetles and start reproducing again between April and late June.

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American Lawngrubs

 

 

There are a number species that may infest American yards. These include May & June Beetles, Northern & Southern Masked Chafers, Bluegrass & Denver Billbugs,  Japanese Beetles and White Grubs. We will have a look at all these pests and show you when to be aware of the most likely time of year that each species will be more prominent in your grass.

 

 


May and June Beetles.

 

c6c57255be1f518 American Lawngrubs

 

June Beetle picture taken by pizzodisevo.


As the name suggests the adult beetles will show up in around May and june and then start to lay their eggs in your grass. The new grubs re not usually such a problem unless there is a large concentration of them. Even then, if your grass is in excellent condition it may withstand an attack without showing too much stress in the form of bare patches. Be warned though that large infestations may bring predators that can dig up your grass to feed on the grubs. The worst time for these species is in the second year of their three year life cycle when they are much larger and just a few grubs per square foot can cause visible damage to the lawn. Between feeding seasons they will dig down below the layer that frost will get to in order to stay alive.


 


Japanese Beetle

 

 American Lawngrubs

Adult Japanese Beetle – Photo by abbydonkrafts

Unfortunately Japanese Beetles can be a problem in the adult phase as well as when a grub and so we should be particularly alert for them as they will eat flowers and leaves of  crabapple, rose, grapes, beans and other plants grown in our yards. Traps for the adults are thought generally only to be really recommended for showing how bad the problem is. These pests having quite noticeable metallic and bright coloration will lay their eggs in mid to late May with the bulk of them being laid before the end of July. You may be fortunate if you have a dry spell as the young larvae are not very tolerant of soil that is dry. Insecticides are probably best used in early summer when the eggs begin to hatch.

 

 

 

Masked Chafers

 American Lawngrubs

 

Picture by dendroica cerulea.


The adult beetles fly n and start laying eggs during june and can go on until mid to late August depending on your location. Once hatched the larvae will start to feed on the roots of your grass, continuing until there is a likelihood of frost with the worst damage occurring from late Summer into early Fall. Once again,location and weather will determine when the grubs stop feeding to go down below the likely depth frost will attain for the winter months. Should your grass be very healthy and vigorous, it will resist these grubs even in reasonably large numbers.

 



Billbugs


These animals are actually weevils and they can sometimes be seen when away from foliage on our driveways and sidewalks in Spring and Late Summer. The females will cut small holes in plant stems in order to lay their eggs inside. The grubs usually have a brown head with the rest of them being white or cream. The first real damage is caused by the younger grubs. They will grow to be a third to half an inch long. The affected grass is easily detached from the soil as the younger grubs will have attacked the area of the plant’s crown and killed it. The root area and lower crown are eaten by the older Billbug larvae. These grubs will often attack new sod lawns and are quite common in all new lawns. The infestations are often more severe near to protective areas such as evergreens. For best effect with insecticides it is recommended to apply in early May just prior to the adults laying their eggs. Spraying later will not do so much good as the young will be inside your plants and more difficult to get at. In some areas you may get better results by spraying for Denver Billbugs in early June and remember that spraying can often be more effective than more solid products. Sprays should be used when there is a greater chance that they will linger on the foliage longer and this usually means dry weather is forecast. There are natural predators such as hunting wasps, birds and even fungal diseases that will help but one of the better ones is the use of parasitic nematodes that can often be bought locally or may be sent by mail order companies.

 



IN BRIEF


There are a number of different insect species whose young are what we generally call lawn grubs. This means that there are different “best times’ to try and kill them off. Some species are best dealt with at the adult stage and others when the larvae are close to the surface of the lawn feeding. Neither chemicals nor introduced parasites will be very effective when the grubs are deeper in the soil because of the physical barrier caused by that dirt. Some chemicals will last longer than others depending on what they are and when they are applied. Nematodes just may outlast all chemicals as they will be carried by the dying grubs and can even live on in the soil waiting for another host to come along.


ALWAYS read and comply with the instructions for your chosen method of lawngrub control.

 

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Sod Webworm

 

There are numerous varieties of sod webworms as well as lawn moths that frequently infest home lawns. They range from silver striped sod to bluegrass sod webworms. Over the last few years a handful of other sod webworms have been discovered in domestic lawns. With these sod webworms becoming more common, so is the major damage that they can cause to residential turf, excruciatingly so in a period of drought that is so damaging to landscaping.


Sod webworms make it through winter weather as mature larvae, and are insulated by their silken tunnels. The larvae resume their processes of feeding in spring, then pupate from May to June. This process takes two weeks and then the adult moths emerge, and take refuge in the grass and whatever brush or shrubbery is around them. Eventually the female moth will lay eggs, up to two hundred of them, and these will hatch into more young larvae another week or two after they are laid. This cycle is not necessarily annual, and can occur more than once a year, making these webworms quick breeders.


These lawn grubs can cause considerable harm to your yard as larvae. You will see large brown patches come up in the lawn, about the size of baseballs. The brown patches are often pierced with pencil sized holes which is because of the birds attempting to chase their prey down in the dirt. Throughout the summer is when most damage from the larvae will be observed. The larvae will chew leaves and stems and essentially feed of your lawn and lead to bigger brown patches in your turf. It will often appear as if there is a drought when there is not, which also gives the larvae a bit of camouflage when drought is actually present in the area.


So due to the large numbers in which the spawn, and the damage that they can cause to the aesthetic look of your lawn, you will want to take measures to combat these nuisances. A non-chemical route to take is reseeding your lawn with endophyte-enhanced turf grass seed. In most instances these seeds are employed the endophytes produce alkaloids which are resistant to insects and various diseases. Make sure to use caution when using these seeds as they can harm the local live stock, make sure that all directions on the label are followed, and you may want to do some research on how to apply these safely.


Parasitic nematodes are another friendly way of taking care of the webworms; however it is important to keep in mind that the nematodes are also living insects and require care when handling and proper irrigation. They are a more fragile treatment to eradicate the webworms, and most be applied delicately.

 

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Australian Lawn Grubs 2 – White Curl Grubs

 

 

 

 

White Curl Grub


lawn grubs such as White Curl Grubs, also known in some places as Cockchafers are the larvae of beetles that feed on the underground stems and roots of plants. These include the Argentine Scarab, Pruinose Scarab, African Black Beetle and some more species native to Australia. The damage they cause may not be too noticeable if the weather is damp and the infestation is not too severe. When the weather is dry, the damage is more likely to show and even lower numbers of these pests will cause worse damage because the plants they are feeding on will already be under stress and not so able to regenerate or withstand an attack. One way to see if your dried out died off lawn does have below ground feeding pests is to see if the grass moves at your touch. A law suffering drought will remain solid but one that has an infestation will slide and shift about where the attack has occurred.


White curl grubs are reasonably well protected by the soil as thy live underground. If you do see them, they can be recognised by the fact that they have three pairs of legs and tend to be shaped like the letter ‘C’. They can grow as long as 2.5cm just before they pupate. The adult beetle is a little smaller being in the region of 1.5cm in length. One way that grubs may be indicated is the behaviour of other animals. If you see meat eating birds such as wood duck, crows and magpies, as well as some other animals like bandicoots. Another method of detection is to put something damp on the grass over night. An old piece of carpet, sacking or something else that will retain moisture. In the morning you will find adult beetles hiding there. There numbers will give an indication of how many eggs have been laid and how serious the problem may be or get. These checks should be done between springtime and summer when egg laying is most likely to be going on.


Eradication.


Having located the pests, we will now move on to getting rid of them. There are some simple measure that may just help. One is to pour some biodegradable soapy water on to the affected area. The lava and beetles are then more likely to rise to the surface where they can be picked off by your garden birds or other grub and bug eating visitors. The beetles are attracted to light, so, turning off outdoor lights when not actually in use may just prevent some of them from coming to your garden.


Another method that is ecologically more sound is to introduce nematodes that are specifically targeted at the insects infecting your grass or crops. These entomopathogenic nematodes usually arrive in a dormant state and have to be moistened so as to reinvigorate them. Be aware though that just adding water will probably not be enough. The mixture will have to be stirred well enough to ensure that they nematodes are distributed equally thought the liquid. Another point to bear in mind is that the area you are going to treat should be doused prior to application. Once again this is to bring the nests closer to the surface so that the nematodes will not have to go so far to find them. One should also put the cure down as it is getting dark because the little helpers may be susceptible to bright sunlight. Once they are applied, the nematodes seek out their hosts and make their way inside through any available orifice. Once inside they disseminate bacteria that create the right conditions for themselves and the nematodes to reproduce until the grub dies. When that happens all the nematodes move away looking for another host to live off.


One can also use chemicals in order to control the numbers of insects. This method is best used on newly hatched grubs because as they get older, their body fat will help them to resist the treatment. Once again you should give the area to be treated a good watering to bring the pests closer to the surface and allow the chemicals easier access to them. Do not forget, if the grubs can not be reached, the cure will not work. Please read and comply  with all warnings and instructions as some of the chemicals authorised for lawn beetles in how lawns can be deadly to humans too. We suggest that you do read all the labels whilst in the store so that you will not buy something that will not suit your purposes, or even worse, do you harm.

 

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Australian Lawn Grubs

 

We’re going to lump the three main things that attack Australian lawns into the category of lawn grubs as that is the name a lot of us know the by. They are all however the offspring of insects. They can sometimes reach plague proportions and completely destroy our lawns or farmers’ crops even though many grasses and cereals can withstand moderate feeding by a reasonable numbers of parasites. We will go through just what they are and how to get rid of them. To start off we will examine Armyworms.


Armyworms.


There are three species of these little blighters although they are all related. These are the Common Armyworm (Leucania Convecta), the Northern Armyworm (Leucania Seperata) and the Sugarcane Armyworm (Lecania Stenographa). The first stage of the lava are only about 1mm long. As they get larger they become more recognisable as they develop stripes along their sides. When it is mature it will get to about 4cms long and have  distinctive stripes along the body with three pale ones on the head and the bit just behind it as well as the tail end. There are no hairs on the smooth bodies. The moth also has a wingspan of about 4cms and is a buff colour. This description will just about fit both Common and Northern varieties with the moth of the Sugarcane species having a dark line on the forewings that are a bit more pale in colour.


The Common Armyworm is native to Australia and found pretty much all over the eastern half of the country. The Northern Armyworm is also found all over the country as well as in New Zealand and South East Asia. The Sugarcane Armyworm has been found in Asia the drier pats of the Australian mainland and sometimes it gets to Tasmania.


The Sugarcane Armyworm is a less of a problem than the others occasionally doing damage to grain crops in Western Australia. The Northern Armyworm tends to cause crop damage in Queensland to plants such as rice, barley, maize, wheat and sorghum. The Common Armyworm will have a go at native grasses in the pastures, perennial grass seed crops as well as wheat, barley and oats.


Life Cycle


All three types are similar and we will describe the Common Armyworm’s life. The adult moths will go to a place they judge to give the best chance of the continuation of their species. They will fly their and lay their eggs on what they consider the best places. This is normally in the cress of cereals or grasses that are drying out or actually dry. The eggs are laid in large clumps by the female numbering up to a thousand at one sitting, being stuck into those folds of the host plant’s leaves. When the lava emerge from their eggs they will use a thin thread of silk to be carried on the wind so as to speed out through the grasses or crops around them. Differences in temperature will control the speed of their hatching and rate of growth. At 20 degrees Celsius they will hatch after about seven days and be read to pupate in another thirty fours days. At thirty degrees these times can be reduced from  two to three days and and thirty four to thirty five respectively. 


Periods of Risk


If you are a cereal farmer, late Winter to Spring is likely to be your worst time. The winter generation can cause quite severe damage to grassland and crops when they gather in large numbers. They will eat virtually everything before moving on to another area. You should be aware that if you sow seed into stubble, the lavae may damage the new growth as it appears. There are usually three generations of Armyworms through the year and it is a good idea to check the bases of plants and under lumps of earth where they hide during the day time. 


Dealing With The Problem


There are a number of different insecticides that can be used to control Armyworms. You must be aware however that these measures are best used when the lavae are a bit smaller, say between one and two centimetres long. If they are bigger than that they are harder to kill and may need quite a bit higher concentration of chemical. As they are more active at night, the best time to spray will be later in the day in order to take advantage of the greater accessibility.


There are also parasites that can help to control Armyworm numbers but these tend to be less effective if there is already a large infestation. This is because they are obviously more slow to act than chemicals. Numbers of Green Carab Beetles will increase quite a lot when there are more Armyworms for them to feed on. Common brown earwigs, shield bugs and some fungal diseases may also help in controlling the pest.

 

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Know Your Enemy

 

Lawn grubs can significantly damage your lawn, and you may not notice significant damage until infestation is well underway. 

Lawn grubs are generally white, and their bodies have a typical “C” shape to them. Grubs are larvae, and if left to mature, will eventually turn into beetles. The most common type of grub is the white grub, with the adult becoming a “chafer” beetle, tan in color. Another common type of grub is the May/June beetle. What’s notable about these two types of common grubs is that while the chafer beetle has a lifecycle of just one year, the May/June beetle has a cycle of three years.

 

Where they hatch and feed 

Grubs generally hatch on lawns that have been well watered, with eggs being laid on the soil in mid summer. The eggs will hatch and damage will occur beginning late midsummer, and may occur right up until early fall season.

 

Monitoring progress

 European chafer beetle has a lifecycle of just one year, while the June beetle has a three-year lifecycle. This may change how you want to manage them.

 

Noting damage

You’ll first note lawn grub damage by noticing that the grass will turn brown. It can be difficult to determine that this is actually lawn grub damage at first, because it looks much like many other things that can also occur at the same time of the year, such as short-term drought or drying of the soil.

 

Taking note of grubs’ stages of growth 

When first hatched, both June and chafer beetles are about 3 mm long, and can grow to sizes of between 2 and 4 cm at full larval stage growth. Beginning about late May or early June for June beetles and June to mid July for European chafer beetles, the beetles will begin to lay their eggs. By mid-June, May or June beetles’ eggs have hatched, and the larva will begin to feed on organic material. This is also true of the European chafer beetles’ larvae.

 

This is where the differences begin to occur between the European chafer and June beetles, though. With the June beetle larvae, the larvae move below the frost line to spend the winter and then reemerge in the spring when warmer temperatures arrive. Upon reemerging, they continue to feed. The same thing happens in the second year, with larvae moving below frost line when cooler temperatures arrive. They pupate in their third year, in June, after they have fed for a short time upon reemerging in the spring.

 

It’s important to note that with the June beetle larvae especially, it’s entirely possible to have larvae at different stages of growth below your frost line at any given time; that means that when you treat this particular infestation, you have to make sure that all stages of larval and adult growth are treated.

 

With the European chafer beetle, it takes one year for the beetle to complete its lifecycle, meaning that it goes through all stages in one year. The larvae hatch as long as there’s moisture present in the root zone, and can stay feeding until November or December. They move below the frost line, and then go back to grass roots and began feeding in early spring; they pupate in May.

 

Treating for lawn grubs 

Sample for infestation in areas you suspect it’s occurring in late fall, and treat then. It would be most effective then, as opposed to spring or early summer treatment. Formulations for insecticide treatments change all the time as new products come out, so check to see which are the most effective on the market at the time of treatment.

 

 

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