Imphal, Jul 6 : Grasshoppers swarming the state need not cause panic as they are of the harmless long-horn variety, according to scientists.
These are not marauding “locusts” but “grasshoppers” which cause less harm to standing crops, assistant professor Kh Ibohal Singh of the department of entomology, Central Agricultural University told IFP today.
He said the sudden rise in the number of grasshoppers is a consequence of untimely rainfall witnessed in the month of January this year and bamboo flowering that occurred in some parts of hill districts of the state.
“There is no need for alarm as these insects which have descended in unusual swarms on Manipur and neighboring state of Nagaland are not the harmful species,” he said.
This family of grasshoppers in fact belong to a beneficial strain and are delicacies in some parts of the world.
However, a team of experts from the state agriculture department has been sent to Tamenglong district where there are reports of swarming grasshoppers.
The team will investigate into the kind of the grasshoppers present there and whether they are the harmful variety, according to the director of the department, RK Noyansana.
The entomology department of the Central Agricultural University while taking note of the swarming insects not only in other parts of the state but also in some places in Imphal area has confirmed the strain of the insects.
Referring to the report of the department, assistant professor, Kh Ibohal said that even though some among the swarming grasshoppers are of a harmful variety to standing crops, 90 percent of them are the long-horn grasshoppers which do not damage crops.
It`s not the “group feeding locusts” which can swarm in groups like bees and destroy standing crops like the occurrence in Pakistan and some parts of India bordering that country some 20 years back, although around 10 percent of the currently swarming insects are of harmful kind like the short-horn grasshopper (acirididae/locustidae).
The currently available insect is not of group feeder type like that of migratory and gregarioud locusts.
Long-horn grasshoppers are individual feeders, i.e. they do not feed on plants in groups unlike the locusts which feed in groups.
Locusts are dangerous as they feed in groups and hundreds of them together eat up a plant which damages the plant totally.
“There is no need to worry for damage to standing crops as the farmers can easily take up measures to control such type of grasshoppers.
However, the apprehension over its effect on flight operations at the airport could prove to be genuine as birds are among the common predators of the insects. Apart from birds, lizards, mantids, spiders, and rodents eat grasshoppers.
Regarding the sudden rise in the number of the grasshoppers in region, he said that it was caused due to the untimely heavy rainfall that was witnessed in the month of January this year in the region which created a large scale hatching of the eggs of the insects in the forests and other barren areas in the region.
Another factor was the damage of the bamboo grooves by the mass scale bamboo flowering in the hill areas of the state.
Mention may be made that mass bamboo flowering was also reported in Churachandpur and Tamenglong districts where the invasion by the grasshoppers has been reported.
Rooting of the bamboo roots where commonly egg pods of the insect are found and exposure in the atmosphere and then rainfall created favourable conditions for hatching of the eggs.
With regard to mating behavior of the insects, he said the female digs a hole and lays the eggs there. They keep the eggs in a pod which is naturally made resistant to air and water for a long time. The egg can remain active inside the “egg pod” for more than 10 years.
The eggs remain unhatched for a long period of time until it is disturbed by sudden change of climatic conditions like heavy rainfall in the winter season, he observed.
As such swarming of this insect is usually witnessed at an interval of around 10 to 12 years in the state as well as in the north eastern states.
He said study into the current swarming of these insects revealed that maximum variety are of long-horn family grasshopper even though very few harmful short-horn grasshopper are found mixed with them.
Elaborating on the control of this insect, he recommended insecticides like chlorpyriphos of 20 EC or cypermethesis of 10 EC.
Chlorpyriphos can be applied to the fields with 25 ml of it mixed with 10 litres of water while cypermethesis can be used by mixing 10 ml of the same in 10 litres of water, he said.
He also said that the most effective insecticide is the Satisfy (content chlorpyriphos and cypermethesis together) having 55 EC.
Another most effective and health hazard free means to control the insects is keeping tubs with water under a light (below a electric bulb). The light will attract the insects which will later fall into the water tub and die in the water, he said.
The kind of grasshoppers found here are also edible ones and is a favourite food item in some parts of the region, he said.
