Which Insect Makes the Biggest Swarm?
Which Insect Makes the Biggest Swarm?
- 1 Which Insect Makes the Biggest Swarm?
- 2 Why Is There A Giant Grasshopper On The Royal Exchange?
- 3 The amazing Giant Weta – the heaviest insect on Earth (70+ grams)
- 4 Giant weta
- 5 Colorado State University
- 6 Extension
- 7 Grasshopper Control in Gardens and Small Acreages – 5.536
- B.A., Political Science, Rutgers University
Honey bees swarm, ants swarm, termites swarm, and even gnats swarm. But none of these swarming insects comes close to holding the world record for the biggest swarm. Which insect makes the biggest swarm?
It’s not even close; locusts make the biggest swarm of any other insects on earth. Migratory locusts are short-horned grasshoppers that go through phases of gregariousness. When resources become scarce to an overcrowded population of locusts, they move en masse to find food and a little «elbow» room.
Just how large is a locust swarm? Locust swarms can number in the hundreds of millions, with densities of up to 500 tons of locusts per square mile. Imagine the ground covered in grasshoppers so thick you can’t walk without stepping on them, and the sky so filled with locusts that you can’t see the sun. Together, this massive army can march hundreds of miles, consuming every last leaf and blade of grass in their path.
According to the Bible, Jehovah used a swarm of locusts to persuade Pharaoh to let the Hebrews go free. The locusts were the eighth of ten plagues suffered by the Egyptians:
«For if you refuse to let my people go, behold, tomorrow I will bring locusts into your country, and they shall cover the face of the land, so that no one can see the land. And they shall eat what is left to you after the hail, and they shall eat every tree of yours that grows in the field, and they shall fill your houses and the houses of all your servants and of all the Egyptians, as neither your fathers nor your grandfathers have seen, from the day they came on earth to this day.»
In modern-day, the record for the biggest swarm goes to the desert locust, Schistocerca gregaria. In 1954, a series of 50 swarms of desert locusts invaded Kenya. Researchers used airplanes to fly over the locust invasion and took estimates on the ground to put the swarm in a numerical context.
The largest of the 50 Kenyan locust swarms covered 200 square kilometers and involved an estimated 10 billion individual locusts. In total, 100,000 tons of locusts descended on this African nation in 1954, covering a total area of 1000 square kilometers. About 50 billion locusts devoured Kenya’s flora.
Why Is There A Giant Grasshopper On The Royal Exchange?
They say it pays to look up in London, for you never know what unusual sights will greet you from the rooftops. This is particularly true around the Royal Exchange, a grand trading bourse turned into a posh shopping centre above Bank station. Look up here and you may notice a spindly-legged form perched high above the streets. Here’s a closeup.
This is the Royal Exchange’s gilded grasshopper weather vane. This ancient insect has lorded over successive versions of the building since the mid-16th century. What could the clicky creature have to do with trade and finance?
The grasshopper was the personal emblem of Tudor financier Sir Thomas Gresham (c1519-1579).
Gresham’s statue on Holborn Viaduct.
Sir Thomas was a hugely influential figure in 16th century London. He founded the first Royal Exchange in 1565, which helped turn London into a global centre of finance. A bequest in his will set up Gresham College, which still puts on regular (and popular) public lectures to this day. And you may well have wandered down Gresham Street by the Guildhall, named in his honour.
But why did this sober man of finance choose a golden grasshopper as his personal emblem?
Legend has it that Thomas’s ancestor Roger de Gresham was abandoned as an infant in the marshlands of Norfolk. The rejected orphan was finally discovered after a woman was attracted by the sound of a chirruping grasshopper. The Gresham family later made good as merchants, and eventually incorporated the insect into their coat of arms, shown below as part of Gresham College’s logo.
That’s what the legend says. More likely, though, it’s probably some ancient pun of Gresh and grass.
The Royal Exchange weather vane is not the only prominent grasshopper in the area. You’ll see the orthopteran mark all over the place when you start looking. Duck down nearby Change Alley (named after the Stock Exchange) and you might spot this stone carving that marks the spot of Garraway’s Coffee House.
Then out on Lombard Street, famous for its hanging signs, can be found this pendant grasshopper.
This sign is really, really old. Pre-fire, in fact. It carries a date of 1563 along with Thomas Gresham’s initials. It marks a former goldsmith’s owned by Gresham, which was later taken on by Martins Bank.
There are many other examples dotted around the City, and at other sites connected with Gresham. We noticed this glazed hopper inside an office block on Basinghall Street, for example.
But the best way to celebrate Thomas Gresham’s vast legacy is to pop along to a Gresham College lecture. These free talks, on every topic from economics to astronautics, are held regularly at Barnard’s Inn in Holborn or the Museum of London. Check out the programme here.
The amazing Giant Weta – the heaviest insect on Earth (70+ grams)
In the small islands of New Zealand, the world’s heaviest insect lives – The Giant weta. There are 70 types of species of weta in the genus Deinacrida of the family Anostostomatidae.
Giant weta is endemic to New Zealand and is an example of island gigantism: which is a biological phenomenon leading to a larger size than their mainland relatives because of their isolation and lack of large predators. A female giant weta filled with eggs can reach up to 70 grams or more!
There are eleven species of giant wētā, most of which are larger than other wētā, despite the latter already being large by insect standards.
The largest species is the Little Barrier Island giant weta. Large species can be up to 10 centimeters (4 in) not inclusive of legs and antennae, with body mass usually no more than 35 grams. But rarely, a female filled with eggs can reach up to 70 grams or more: one captive female reached a mass of about 70 grams (2.5 oz.), making it one of the heaviest documented insects in the world and even heavier than a sparrow.
The largest species of giant weta is the Little Barrier Island giant weta, also known as the wētāpunga, which means the “god of ugly things” in the Maori language. One example reported in 2011 weighed 71 grams, and a 72 grams specimen has been recorded.
Most populations of this amazing insect have been in decline since humans began modifying the New Zealand environment. All but one giant weta species are protected by law because they are considered at risk of extinction. When humans arrived in New Zealand hundreds of years ago, they inadvertently brought weta predators along with them, like rats and cats, which ate the insects.
To help safeguard this threatened species, an experimental breeding project was successfully undertaken by the staff at Butterfly Creek in South Auckland under the guidance of the Weta Recovery Group. Auckland Zoo was extremely successful at breeding hundreds of wētāpunga.
Little Barrier Island (Hauturu in Māori language, means “the resting place of the wind”), lies off the northeastern coast of New Zealand’s North Island. Located 80 kilometers (50 miles) to the north of Auckland, the island is separated from the mainland to the west by Jellicoe Channel, and from the larger Great Barrier Island to the east by Cradock Channel.
The island is an extinct andesitic volcanic cone, roughly circular in shape, about 6 kilometers (3.7 miles) across, with an area of 28 km 2 (10.8 square miles).
Approximately 40 species of rare or endangered birds, 14 reptile and 2 bat species, and more than 400 native plants live in the Little Barrier Island, according to the New Zealand Department of Conservation (DOC).
Visitors need a permit from the DOC before visiting the island.
The giant weta is usually less social and more passive than other weta species. Their genus name, Deinacrida, is Greek for “fierce grasshopper”. Its diet consists of plants (even carrot!), other small insects and fruit.
Another amazing fact about the wētāpunga: many species are alpine specialists (live in high altitudes). Five species are only found at high elevation in South Island. The scree weta (D. connectens) lives about
1200 meters (3,920 feet) above the sea level and freezes solid when temperatures drop below -5°C (23°F).
Colorado State University
Contact your local county Extension office through our County Office List.
Grasshopper Control in Gardens and Small Acreages – 5.536
by W.S. Cranshaw and R. Hammon * (1/13)
- Grasshoppers are the most difficult insect to control because they are highly mobile.
- All grasshoppers lay their eggs in soil.
- There are over 100 species of grasshoppers in Colorado.
- During periods when local outbreaks are developing, control usually involves using sprays or baits.
Grasshoppers can be the most noticeable and damaging insects to yards and fields. They also are among those most difficult to control, since they are highly mobile. For many reasons, grasshopper populations fluctuate greatly from year to year, and may cause serious damage during periodic outbreaks. Problems tend to increase beginning in early summer and can persist until hard frosts.
Over 100 species of grasshoppers occur in Colorado and their food habits vary. Some primarily feed on grasses or sedges, while others prefer broadleaved plants. Other grasshoppers restrict their feeding to plants of no great economic value and a few even feed primarily on weed species (e.g., snakeweed). However, others will readily feed on garden and landscape plants (Table 1).
Among vegetable crops certain plants are favored, such as lettuce, carrots, beans, sweet corn, and onions. Squash, peas, and tomatoes (leaves, not fruit) are among the plants that tend to be avoided.
Grasshoppers less commonly feed on leaves of trees and shrubs. However, during outbreak years even these may be damaged. Furthermore, grasshoppers may incidentally damage shelterbelt plantings when they rest on twigs and gnaw on bark, sometimes causing small branches to die back.
|Figure 1. Differential grasshopper.||Figure 2. Migratory grasshopper.|
|Figure 3. Twostriped grasshopper.||Figure 4. Redlegged grasshopper.|
|Figure 5. Clearwinged grasshopper.|
Grasshopper Life History
All grasshoppers lay their eggs in soil, in the form of tight clustered pods. Relatively dry soils, undisturbed by tillage or irrigations, are preferred. Egg laying may be concentrated at certain sites with favorable soil texture, slope, and orientation, producing ‘egg beds.’
The egg stage is the overwintering stage of most, but not all, grasshoppers. For the majority of species the eggs hatch in mid- to late-spring, varying with soil temperatures. At egg hatch the tiny first stage nymphs move to the surface and seek tender foliage on which to feed. The first few days are critical to survival. Adverse weather or absence of suitable foods can cause high mortality. Surviving grasshoppers continue to develop over the next several weeks, usually molting through five or six stages, before ultimately reaching the adult form.
Adult grasshoppers may live for months, interspersing feeding with mating and egg laying. Species that winter in the egg stage die out in late summer and early fall. A few species, perhaps most conspicuously the speckledwinged grasshopper, spend winter as a nymph, remain active during warm periods, and may develop to the adult form by late winter.
|Figure 6. Grasshopper egg bed.|
The most important factors are weather related, particularly around the time of egg hatch. For example, cold, wet weather is very destructive to newly hatched grasshoppers. However, very dry winter and spring conditions also can be harmful to survival since required tender new plant growth is not available.
Some insects commonly feed on grasshoppers. Many species of blister beetles (see fact sheet 5.524, Blister Beetles in Forage Crops) develop on grasshopper egg pods and blister beetle abundance cycles along with their grasshopper hosts. Adult robber flies are common predators of grasshoppers during summer and other flies develop as internal parasites of grasshoppers. Many birds, notably horned larks and kestrals, feed heavily on grasshoppers. Grasshoppers are also frequently eaten by coyotes.
Grasshoppers are also subject to some unusual diseases. A fungus (Entomophthora grylli) infects grasshoppers causing them to move upwards and cling to plants shortly before they kill the insect host. Stiff, dead grasshoppers found stuck to a grass stem or twig indicate infection with this disease. A very large nematode (Mermis nigriscens) also sometimes develops in grasshoppers. Both the fungus disease and nematode parasite are favored by wet weather.
|Table 1. Primary grasshoppers that damage gardens
and small acreage pasture areas in Colorado
|Common Name||Scientific Name||Comments|
|Differential grasshopper||Melanoplus differentialis||Often one of the first grasshoppers found moving into
gardens and one of the largest in the genus Melanoplus.
|Migratory grasshopper||Melanoplus sanguinipes||Often the most damaging species to croplands. Any early
hatching species and capable of long migration flight.
|Twostriped grasshopper||Melanoplus bivittatus||Often the most common species damaging gardens, it migrates
from empty lots, roadsides, and other undisturbed sites. It often
hatches in late spring, a few weeks later than many grasshoppers.
|Redlegged grasshopper||Melanoplus femurrubrum||A widely distributed grasshopper that feeds on many
garden plants. It tends to be most abundant in moist sites and is
one of the later hatching species.
|Clearwinged grasshopper||Camnula pellucida||The primary species present in recent outbreaks reported
in areas of the West Slope and around Steamboat Springs. An early
hatching grasshopper that restricts feeding to grasses.
Managing Grasshoppers with Baits and Sprays
During periods when a local outbreak develops, control usually involves using sprays or baits. To be successful these need to be applied to developing stages of grasshoppers and concentrated at sites where egg laying occurs. Ability to control grasshoppers declines as grasshoppers develop and migrate.
Surveys of grasshoppers can be very useful in anticipating problems and treating appropriately. Numbers of grasshoppers present in late summer and early fall can be a good indicator of problems the subsequent year. Follow-up surveys the following spring to detect young nymphs can determine when eggs have hatched. Area-wide surveys may locate egg beds and other sites where early season activity originates.
Treatments should be directed at the young grasshoppers and nearby vegetation present in these breeding sites. At lower altitudes, this often occurs in May; early June may be the optimal time for grasshoppers at higher elevations. Sprays of insecticides are most effective at this time and several insecticides are effective (Table 2). Insecticide options are greater for larger acreages and unit costs are less expensive. The addition of canola oil to insecticide sprays can improve control by making treated foliage more attractive to feeding grasshoppers.
Alternately, baits containing carbaryl (Sevin) can be broadcast. Bait formulations are made by mixing the insecticide with bran or some other carrier and kill grasshoppers that feed on the bait. These treatments limit application effects on other insects present in the treated area. However, availability of Sevin baits is frequently limited, or prohibitively priced for use on large areas. Baits must be reapplied after rain.
Insecticide treatments do not need to completely cover the area since grasshoppers are mobile. Insecticides applied as bands covering 50 percent of the area, or even less, have proved very effective for control of grasshoppers in rangelands. Backpack sprayers and application equipment modified for use on ATVs can be used in larger acreages. A review of this method, known as Reduced Area Acreage Treatments (RAATS) has been prepared by the University of Wyoming at: www.sdvc.uwyo.edu/grasshopper/atvraats.htm
Where grasshoppers develop over large areas and impact several properties, coordinated area-wide control is very useful. As this requires some additional preparations in planning, early surveys are even more important. Grasshopper control often is much more successful as a community effort.
Once grasshoppers have reached the adult stage and migrations occur, some insecticides may be applied directly to plants. Such applications have only short effectiveness and damage can occur before individual grasshoppers are killed. Furthermore, the choice of insecticides is more limited since few allow direct application to garden fruit and vegetables.
|Table 2: Insecticides used to control grasshoppers.|
|Common Name||Trade Name(s)||Labeled Uses, Comments|
|carbaryl||Sevin||Most formulations allow use on a wide variety of fruits and vegetables
(1-14 day preharvest interval). Available for use as sprays, dust
and in baits.
|acephate||Orthene||Has systemic activity in plants and may persist longer than most
other insecticides. Uses are limited to non-edible crops.
|permethrin||Many trade names.||Widely available for garden use and most formulations allow use
on a wide variety of fruits and vegetables. Fairly short persistence
of effect for grasshopper control.
|diflubenzuron||Dimilin||Growth regulator that affects chitin formation as grasshopper nymphs
molt. Effective only on immature insects but has long residual activity.
Restricted Use insecticide. Most use will be by licensed pesticide
applicators on pastures.
|Nosema locustae||NOLO Bait, Semaspore||A biological control that produces infection from a
protozoan. It is relatively slow acting and only effective against
young grasshoppers. Use allowed in Certified Organic crop production.
Nosema locustae Baits
Baits containing the protozoan Nosema locustae is a biological control option that may be considered for treating grasshopper breeding sites. This is sold under the trade names NOLO Bait or Semaspore and can produce infection of many species of grasshoppers. Because it is selective in effects, only affecting grasshoppers, its use is sometimes considered desirable.
There are some limitations to Nosema locustae baits. Only young grasshoppers are susceptible, and it can not be used effectively after adult migrations have occurred. It is also fairly slow acting and does not equally infect all grasshopper species. Often it is most effectively used in a long-term grasshopper management program, in combination with other controls.
Nosema locustae baits are also perishable. They are best kept refrigerated before use. Expiration dates are usually printed on packages and should be checked.
Some Interesting and Unusual Grasshoppers
Among the 100-odd species of Colorado grasshoppers are some that may attract attention because of unusual size, coloration or habit (Table 2). None of these are damaging to gardens and croplands because they do not develop outbreak populations or limit their feeding to plants that are not economically important.
Speckledwinged grasshopper (Arphia conspersa) – This is the grasshopper most commonly observed during warm days of winter and early spring. Eggs of the speckledwinged grasshopper hatch in mid-late summer and they spend winter as nymphs and, later, adults. The adults have colored hindwings, often with a yellow or reddish spot and in flight they make a crackling noise. They limit their feeding to grasses and sedges.
|Figure 7. Specklewinged grasshopper.||Figure 8. A mating pair of plains lubber grasshopper.|
Plains lubber/Homesteader (Brachystola magna) – This is the largest grasshopper found in the region, an may exceed 3 to 4 grams in weight. It has stubby wings and it is flightless, but can be often seen in midsummer slowly hopping across rural roads in eastern Colorado. The body is colorful, with a mixture of green, pink and brown. The plains lubber will feed on many plants, but is most commonly associated with patches of sunflowers.
|Figure 9. Carolina grasshopper|
Carolina grasshopper (Dissosteira carolina) – A grasshopper commonly disturbed to flight when walking along open areas of bare earth. The hindwings are dark with a light band along the edge and in when flying may hover and produce a faint audible noise. Overall color ranges are light greyish yellow to reddish brown and they often blend well with soil background. They feed on a variety of plants but rarely become abundant enough at a site to cause any serious damage.
Barber pole grasshopper/Pictured grasshopper (Dactylotum bicolor) – This is the most colorful grasshopper found in the state with markings of reddish orange, black and yellow. It occurs in areas of the eastern plains and adults are present in late summer. They feed on broadleaf plants, but usually only those of low forage value and it is not considered a pest species.
|Figure 10. Barber pole grasshopper, late stage nymph.|
Greenstreaked grasshopper/Snakeweed grasshopper (Hesperotettix viridis) – A bright green, colorful grasshopper found throughout much of the state but most common on the eastern plains. It feeds on a limited number of plants, including many that are considered rangeland weeds (e.g., snakeweed, ragweed).
Red shanks (Xanthippus corallipes) – A large grasshopper active earlier in the year than most species. The body color is irregularly splotched and banded, allowing it to camouflage on bare soil. However, the hindwings are bright pink, orange or yellow. It is a grass feeder found in dry, prairie areas.
Spotted bird grasshopper/Lined bird grasshopper (Schistocerca alutacea) – A very long grasshopper (ca. 2-inch long) and strong flier. The lined bird, S. a. shoshone, is found along riverways and moist ravines where it feeds on various shrubs. The Great Plains/sandhills subspecies, S. a. lineata, is found in dry, shrubby areas with large weeds. Adults are present in late summer and early fall but are never very abundant.
|Figure 11. Mormon cricket female. (Photo courtesy John Capinera.)|
Mormon cricket (Anabrus simplex) – This large insect is neither a cricket nor a true grasshopper, but a longhorned grasshopper (Tettigoniidae family), related to a katydid. It lives on the open sagebrush/grassland rangelands of the Colorado Plateau and Great Basin at elevations between 6,500 and 11,000 ft. It attracts attention because of periodic massive migrations of millions of individuals that may devour significant amounts of vegetation. Mormon crickets prefer broadleaf plants, but will also eat range grasses and many crop plants.