White Grub

Scarab beetle larvae are what are often referred to as white grubs. Phyllophaga, Cyclocephala, and Popilia are the most common genera of different types of grubs. True white grub species are members of the Phyllophaga genus. The larvae of scarab beetles became known as white grubs as a result of this species. Annual white grubs, on the other hand, are members of the Cyclocephala genus. May-June beetle is the adult stage of the white grub larvae of the Phyllophaga species. The following is a picture of a real white grub and a June beetle:

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Images: White Grub

How To Identify A White Grub

White grubs are usually white or cream in colour. They are found in the shape of a C. Because of sclerotin, their heads have turned rigid and brown in colour. They feature a gleaming, transparent tail segment on the other end. When entirely straightened out, a fully grown larvae will reach a length of 38 mm. These are some of the most obvious exterior characteristics that help you identify a white grub. These can be seen clearly in the image of a true white grub above. The white grub larvae typically go through three developmental phases, called as instages.

True white grubs and other white grubs have a few other distinguishing characteristics. On the tail-end of real white grubs, there are two distinct parallel rows of stiff hairs. It has the look of a zipper. The yearly white grubs, on the other hand, have dispersed hairs in the same place. The only difference is that they don't have the stiff hairs in parallel rows. Other physical characteristics include the Popilla beetle's two rows of spines arranged in an inverted V form. The design can be found on the abdominal segment's underside.

The brownies and heavy bodies of adult May or June beetles make them immediately identifiable. They are approximately 25 mm in length. After dark, the beetles might be spotted around light sources. With the sound of their hit, the buzzing on the screens of open windows, you can identify a white grub beetle. The adult of the annual white grubs, which belong to the genus Cyclocephala, is smaller than the May-June beetles. They range in size from 11 to 13 mm. Some species are brown, while others have a dull greenish appearance with a metallic head. Furthermore, their thorax resembles that of the Japanese beetle. The adult Japanese beetle also has lustrous copper brown wing coverings and a metallic green or greenish head and thorax. They also have tufts of white hair near the end of the abdomen that are easily identifiable.

One point to note is that there are no white grub worms. Although, commonly they may be called as worms or fat white worms typically, white grub worms are not at all worms. As clarified above any of the white grub or fat white worm are part of a life cycle of the scarab beetle.

The Life Cycle Of White Grubs

In the Northern Plains, the real white grub life cycle lasts 3-4 years (known as semivoltine), but the annual and Japanese beetle white grubs only produce one generation per year (termed univoltine). The biology of the three white grubs is very similar, save from the time it takes for a generation to mature.

From late spring through early summer, adults emerge and fly to neighbouring trees. The willow, cottonwood, poplar, oak, hickory, and walnut beetles feed on the leaves of deciduous trees between May and June. Some of the white grub in groundnut are also seen to emerge. Female beetles that have been mated drop or glide to the ground and lay eggs in the soil later. The egg-laying sites of May or June beetles appear to be grass sod. The larvae feed on the roots of surrounding host plants just a few inches below the soil level, and the eggs hatch in a few weeks. True white grubs dig deep into the ground below the frost line and overwinter as larvae in earthen cells when winter approaches and soil temperatures decrease (first 2-3 years of true grubs). The majority of white grub damage occurs during the second year of the real white grub life cycle, when the grubs migrate up to feed on plant roots voraciously. They overwinter as adults in the earthen cell where they pupate in late summer or fall during the genuine grub's final winter. True white grub larvae move back up in the spring and feed on neighbouring host plant roots all summer.

True white grubs have been observed to attack corn planted after sod, despite their preference for grasses. One species (P. implicita) affects corn planted on constantly cropped, coarse-textured soils, such as sands to loam soils, near cottonwoods, poplars, and willows in western Minnesota and eastern North and South Dakota. Infestations of grubs in soil are heavily impacted by soil texture, and they are unlikely to be a problem in clay soils that are poorly drained. The observed white grub in groundnut belong generally to three.

Annual and Japanese beetle grubs spend the winter in soil cells as larvae. These white grubs travel closer to the soil surface in the spring to feed on plant roots, although the extent of their eating can be highly varied, and often non-economic. They pupate shortly after that. In late June to early July, adults emerge, mate, and deposit eggs. The remainder of the summer is spent by hatching larvae feeding on suitable host plants.

In late June, European chafers lay their eggs, while Japanese beetles lay their eggs in July and August. Within one to two weeks, the eggs hatch and the baby grubs begin eating on grass roots. Many eggs perish from moisture stress due to dry soils in July and August. Grubs eat until the fall, then burrow deep into the ground to survive the winter.

Grubs crawl upwards to grass roots in the spring, continue to feed until late May, and then convert into pupae. Adult Japanese beetles emerge in the first week of July, two weeks before European chafers.

As grass begins to turn brown owing to root damage, evidence of a white grub infestation develops. To uncover grubs, the turf is usually thrown back like a rug. The presence of grubs is indicated by mole or skunk damage.

Plant Injury & Damage & Management Approaches

White grubs feed on plant roots and reside underground. While grasses are usually the target of larval damage, white grubs also eat maize roots. Stunting, nutritional inadequacies, and stand loss may occur as a result of feeding. Corn that has had its roots excessively trimmed seems stunted and easy to uproot. The larvae, especially the older grubs, can feed quickly and migrate from root to root within the row. Stand loss in corn-soybean rotations is usually more severe than in soybean rotations. Damage from tillage of grass pastures or CRP may be severe the second year, when grass roots have degraded to the point that white grubs can only consume corn roots. Overall, substantial economic harm caused by white grubs on soybeans is uncommon, and it usually happens when large populations of grubs are present.

Crop rotation does not provide appropriate white grub control due to their protracted larval development. If tilled after grubs have returned to the root zone, spring tillage may lower white grub populations by killing white grubs near the surface. Plowing with a moldboard moves the dirt over, exposing grubs to birds.

White grub numbers are better estimated in the late summer or early fall than in the spring. Soil samples should be taken in 1 ft2 (0.09 m2) increments, around 8 inches or 0.2 m deep. At least thirty samples should be gathered per field. The sampling locations are chosen at random around the field boundaries, about 45 yards (41 metres) parallel to the shelter belt. White grub control may be necessary on areas of the field that are within 20 yards (18.2 m) of the tree line if less than 40% of the samples contain one or more white grubs. Control is required on areas of the field within 45-65 yards (41-59.4 m) of the tree line if 40-60% of the samples contain one or more white grubs. Control is required on areas of the field within 90 82.3 m of the tree line if more than 60% of the samples contain one or more white grubs. Seed treatment or a soil pesticide sprayed during planting the following spring are two chemical control strategies.

Natural enemies attack white grubs in a variety of ways. Entomopathogenic nematodes, such as Steinernema or Heterorhabditis spp., attack insects and can be found in practically all soils. Bacterial infections afflict white grubs, such as milky spore Bacillus popillae. Commercially accessible nematode and bacterial illnesses are available for gardens, lawns, and water courses, but they are prohibitively expensive for field crops. Beneficial insects such as ground beetles, ants, and parasitoid wasps all contribute to mortality. Finally, white grub larvae will be eaten by vertebrate predators such as skunks, small animals, and birds.

Other popular procedures include: Cultural Practices - Healthy lawns cut at 2" or higher can withstand a lot of insect feeding without harm. Unless there is evident or serious damage, lawn pests do not need to be handled every year.

Monitoring - In order to prevent grass losses, proper monitoring and identification are essential. Sift through the top 3" of dirt, roots, and thatch with a spade to confirm a grub infestation. Larvae of creamy-white C-shaped beetles with tan to rusty-brown heads and six legs can be found. Replace the grass and water it after inspecting the soil. It's not unusual to come upon a grub now and again, and it's nothing to be concerned about. A healthy turf can usually recover from the root damage caused by a few grubs. Damage thresholds differ based on the grub type and the turf's grade.

Biological White Grub Control - White grubs are attacked by a variety of predators and parasitoids, but their efficiency in controlling them is unknown. Milky spore and parasitic nematodes are two white grub biological control agents that are accessible. Only the Japanese beetle is affected by the biological agent that causes milky spore disease. Be aware that, according to research, the milky spore bacterium is ineffective in northern New England due to the chilly spring soils. Because of the high temperature variations in New Hampshire soils, the parasitic nematode can limit white grub populations, but it requires moist soil conditions and has shown minimal survival.

Chemical Control - Chemical controls and application timing change depending on the grub type. Preventive controls should be used from April to mid-July, and curative controls should be used from late July to August.

European chafer grubs can be found across the Lower Peninsula of Michigan, as well as much of the Upper Peninsula. European chafers are a considerably bigger concern than they used to be on a regional level. Only New York, Pennsylvania, Massachusetts, Delaware, New Jersey, Connecticut, New Hampshire, Vermont, Maryland, Southern Michigan, and eastern Ohio had them in 2002. It has now spread across Ohio, Michigan (the entire Lower and Upper Peninsulas), northern Indiana, and eastern Illinois. In 2013, it was also recorded in Wisconsin. It's a problem in Ontario and Vancouver, Canada, so Washington State is keeping an eye out for it.

Japanese beetle grubs eat on turf roots in residential lawns as well, but they are usually less of a concern than European chafers on home lawns. The majority of eggs are laid by Japanese beetles and European chafers in July, however Japanese beetles continue to lay eggs into August. Japanese beetles prefer irrigated turf, such as golf courses, sporting fields, and well-kept lawns, to deposit their eggs. If we have much rain in July, they can be profuse in non-irrigated house lawns, but they are scarce in lawns that are quite dry in July and early August. In the southern half of the Lower Peninsula, south of Lansing, we don't appear to be getting as many complaints about lawns harmed by Japanese beetle grubs, but we are getting more calls from the northern Lower Peninsula as Japanese beetles continue to spread northward. Japanese beetles have been found in isolated sites as far west as Colorado, and Wisconsin, Minnesota, and Iowa have now joined the club of Midwest states with a lot of them.