How long does it take for locust to come back around..is it every 17 years or every seven?

Answer 1

You might be confusing Cicadas and locusts. One species of cicada, aptly named the 17-year cicada only has adult emergence every 17 years. Locusts on the other hand are not so long lived.
Locusts (short-horned grasshoppers) are not as predictable as cicadas. A locust swarm is determined by density of the population. If after lets say 5 years the population of a given species of locust gets too high, the stressful condition causes them to become a swarm. They will actually get larger, change color and will swarm in the millions. The rise in population density is related to many things, like climate, temperature, precipitation, and food availability to name a few.
So, it all depends on environmental conditions and is not pre-programmed like the cycle of the 17-year cicada.

Hope this helps!

Answer 2

It depends on the kind of locust/cicada. As one
answer pointed out the name locust properly
belongs to a kind of grasshopper, but it has been
used for cicadas, also. The life cycle of a cicada
depends on what kind it is. I think the shortest
life cycle is 4 years, but perhaps some are shorter.
There is more than one brood of some of them, so
the same species may be present every year, even though it takes an individual 4 years to mature. The so-called periodical cicadas have a
life cycle of 17 years in the northern part of their
range and 13 years in the southern part.

Answer 3

Cicadas are often also called locusts. The name locust, however, as in the bible reference to someone eating locusts and honey, properly refers to the short-antennaed grasshoppers. Male cicadas are the insects that sing loudly during the day in summer. There are dozens of kinds of cicadas, and only 3 very similar ones emerge every 17 years in the northern half of the U.S. Further to the south the same three emerge every 13 years. Other kinds require less time to become adult. The shortest time I have heard of is 4 years. There are different broods of each species, so many of the more rapidly developing ones are present as adults every year. The adult cicadas do note bite, nor do they feed in the adult stage. The laying of eggs by the females, however, damages twigs of trees. They have a saw-like egg-laying apparatus, and cut slits in tree twigs, in which they lay the eggs. When there is a large emergence of the 13 or 17 year kinds, killing of terminal twigs of trees by the egg laying is very conspicuous.

Answer 4

17

Answer 5

"Generally speaking cicadas have life cycles that last from one to several years, most of this time is spent as a nymph under the ground feeding on the xylem fluids of plants by piercing their roots and sucking out the fluids. Some species take a very long time to develop and the periodical cicadas of the genus Magicicada of North America are well known because some of them have a 17 year life cycle."

Answer 6

locusts are just grasshoppers that adopt a phenotype and associated behaviours when they are exposed to the right environmental cues. it all depends on the population densities when the grasshoppers hatch.

incidentally, you're thinking of cicadas.

Answer 7

Lord, it seems like ours come every year, but there are multiple types, soooooo, check Wiki

http://en.wikipedia.org/wiki/Locusts