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Earwigs Life Cycle Stages – A Complete Circle

Earwigs or as some call them pincher bugs are tiny insects that can be as small as 5mm and as big as 50mm. They are often taken to be as Staphylinid beetles but have one significant difference – their pincers called cerci. Their bodies range in hue from brown to black. It is in the months from July to September that adult earwigs are seen out and about. During winters, the male population dies.

What Is The Life Cycle Of An Earwig – The Beginning

The life cycle of an earwig varies as per the species of which there are 20. Most species do follow the same basic pattern that begins with mating. In late summer or early autumn male and female earwigs will copulate and then build a nest to overwinter. It is here in the subterranean tunnel, either naturally formed or excavated that an adult female will lay “two batches of round, creamy colored eggs every year.” She stands guard over the batch which may contain up to eighty eggs.
What Is The Earwig Lifespan?
From egg to adult, it takes twenty to seventy days of development. The lifespan includes an incomplete metamorphosis, i.e., hemimetabolous. The life stages are gradual and move from egg to nymph to the final adult.
Stage 1 – Egg
A just deposited egg is:

  • Pearl white
  • Elliptical
  • 0.85mm – Width
  • 1.13mm – Length

The eggs are always laid in clusters and within 5cm of the soil surface. The first cluster has an average of thirty to sixty eggs and the second has 15 to 30 only. It is not necessary that a second cluster is produced like in Quebec. The egg stage of an earwig lasts for:

  • 56-85 days in winters ( 1st cluster)
  • 20 days in spring (2nd cluster)

The female earwig keeps moving the eggs inside the cell so that mold or parasite doesn’t develop on them. The size of the egg doubles at the time of hatching through absorption of water.
Stage 2 – Nymph
The eggs hatch in May (1st brood) or June (additional brood). The larvae termed as nymphs come out and consume the egg casing. During this juvenile stage, the earwigs look very much like adults. The earwig nymph size, the one difference from adults, is just 1/8th of an inch. They undergo molting where they shed the outer skin layer 4-5 times. With each shedding they grow in size, the wings elongate and antennae lengthen. From the date of hatching their lifespan is of one year.
The Earwig Life Cycle 5 Instars
Each earwig nymph undergoes development phases between the molts. They are called instars. The alterations that occur in each instar are:

  • The cerci grow in size with each stage.
  • From grey tinged brown to dark brown, the color of the body darkens slowly, but the legs remain a pale shade.
  • The wings become apparent in the 4th instar.

Some Instar Statistics:
Instar 1:

  • Mean head capsule width is 0.91mm
  • Mean body length is 4.2mm
  • 8 antennal segments
  • The time period is 11 to 15 at 15-21 degree Celsius. In field conditions, the time taken is 18-24 days.

Instar 2:

  • Mean head capsule width is 1.14mm
  • Mean body length is 6.0mm
  • 10 antennal segments
  • The time period is 8 to 14 at 15-21 degree Celsius. In field conditions, the time taken is 14-21 days.

Instar 3:

  • Mean head capsule width is 1.5mm
  • Mean body length is 9.0mm
  • 11 antennal segments
  • The time period is 9 to 15 at 15-21 degree Celsius. In field conditions, the time taken is 15-20 days.

Instar 4:

  • Mean head capsule width is 1.9mm
  • Mean body length is 9.0mm to 11.0mm
  • 12 antennal segments
  • The time period is 14 to 19 at 15-21 degree Celsius. In field conditions, the time taken is 20 days.

Mother Earwig’s Role:
The female earwig protects the nymphs by staying inside the cell or near it till the 2nd instar is reached. During this instar, the nymph will go out to look for food during the night. At daytime, they return to the nest. It is at the 3rd and 4th instar that they are dark enough to forage alone. If the earwig stays in the nest even after adulthood, it might be eaten by the mother.
Stage 3- Adult
The winter cluster nymphs reach adulthood in August, and the spring cluster matures as August ends. In some regions, like Washington, the laying of the egg and subsequent stages tend to happen 30 days earlier.

Adult Earwigs Life Cycle Facts – The Formation

  • The shell is shed with maturity as it is not flexible and incapable of growth by itself.
  • As the form comes out of the shell, it is soft and white in shade.
  • As the adult forms, the skin color darkens, and a hard, durable shell is formed. This process is termed as sclerotization and the hard skin is called sclerotized.
  • When there is enough food, earwigs can reproduce in warm temperatures so that new adults are formed before the season ends.

Splendidly Different From Others
The lifecycle of earwigs makes it apparent that they are distinct from other insects. For most insects, the work is done after the eggs are laid. They do not bother about providing safety and food to the hatchlings. Earwigs, on the other hand, surprisingly take care of the nymphs. They protect and feed them till the start of adulthood is reached.

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