Pests can cause serious damage to your property if they are left untreated. This is why it’s important to understand their life cycle so that you can use Armis Pest Management methods at the right time.
A pest’s life cycle consists of several stages that vary in length. Understanding these stages helps you to prevent pest infestations by targeting them at the most vulnerable stage of development.
Egg Stage
The life cycle of an insect is divided into four distinct stages – egg, larva or nymph, pupa, and adult. Pests that have a complete life cycle include beetles, moths, caterpillars, and leaf-feeding beetles (caterpillars). Those with an incomplete life cycle can cause damage at more than one stage. For example, ants can damage plants in the egg, larva, and adult stages.
Many pest species lay eggs in damp soil or other substrates. The eggs then hatch into a larva or nymph, which feeds on organic material until it matures. The larva or nymph then goes through several molting stages and transforms into a pupa before it becomes an adult. Depending on the type of pest, the egg and larval stages can have significant negative impacts on crops.
In some cases, pests can be controlled by targeting specific life cycles. For example, mosquitoes require standing water for breeding, so interrupting this phase with proper preventative measures can help control their numbers. Flies also have an aquatic phase, and disrupting their reproduction can significantly reduce their impact on humans, animals, and gardens.
Flies’ mating behavior involves males displaying elaborate courtship displays to attract females using scent, sound, and visual cues. They can lay up to 500 eggs in a single day and select locations near decaying organic matter where they will lay their eggs. Once hatched, fly larvae are voracious feeders and play an important role in breaking down organic matter and recycling nutrients.
When beetles and moths lay their eggs in or on a plant, the young larvae burrow into the soil, feeding on roots and tubers, leaves, flowers, and fruits. This damages the plant and can result in stunting or death. The length of the larval or nymphal stage can vary from less than 30 days to one or more years for different kinds of beetles.
Bean leaf beetles and hornworms also have a damaging larval or nymphal stage, and both the beetles and their nymphs can damage fruit. As the name suggests, these insects attack beans and legumes, but they can girdle tomato and pepper plants as well.
Larval Stage
Once a pest species’ eggs hatch, it enters the larval stage. The larva is a specialized feeding stage that doesn’t look very much like the adult pest and has unique characteristics and behaviors of its own. Larvae consume food to grow and develop, shed their skin several times (this is called molting), and may even be able to suck liquids out of plants that they are eating.
The frog hopper is a good example of a larva that can suck out the liquid of its prey. Its larval mouthparts are specially adapted for this purpose. It also allows the hopper to move rapidly in search of new food, which can lead to higher encounter rates and feeding success.
After the larva reaches maturity, it becomes a pupa. The pupal stage is a non-feeding and immobile stage of the life cycle. It’s during the pupal stage that many pests become most vulnerable to preventative and control measures.
It is important to understand the importance of this life-cycle stage when planning pest control activities. By knowing that pests are most vulnerable during this period, you can target prevention and control measures at the most effective time. This could prevent the development of a pest infestation from occurring or becoming unmanageable on your property.
Many animal species have a complex life cycle that contains distinct postembryonic stages – namely, egg, larva or nymph, and adult. The development of these separate life stages, known as metamorphosis, gives the individual species the ability to adapt and occupy different ecological niches. For instance, barnacles and tunicates have pelagic larvae that move to a suitable habitat before molting to settle into their adult form. Likewise, the larvae of sea-floor invertebrates such as mussels and crabs need to move into a new territory when they mature into nauplius forms. This process is also known as dispersal.
Pupa Stage
Insects that undergo complete metamorphosis have a pupal stage as well. The pupal stage usually takes place in a cocoon or some kind of protective case. Inside this, the insect goes through major changes to become an adult. Some pests, like mosquitoes, emerge from the pupal stage ready to seek blood for reproduction. Others, such as rodents, spend a good portion of the year in their pupal form before they’re ready to reproduce and cause damage.
As the larva reaches the end of its final instar, it secretes special cells that will transform it into an insect adult. These cells are called imaginal discs. The imaginal discs rest dormant until some cue (temperature, day length, growth, etc) triggers the hormones that will kickstart the pupal process. Once triggered, the larva sheds its outer layer of skin. As it does so, the imaginal discs assemble into the insect’s new, mature body.
During the pupal stage, insects remain inactive. The exception is some ant species, which can move around while in the pupal phase. These ants are sometimes referred to as “nymphs.”
The transformation from larva to adult can take a couple of weeks, a few months, or even a few years. It all depends on the temperature and the species. If it’s cold, the process will slow down considerably.
A few insect groups don’t have a pupal stage, such as cockroaches and crickets. In this case, the newly hatched nymph looks much like the adult insect it will eventually become. The only difference is that the adult nymph may have wings or reproductive organs. This type of nymph is sometimes called an object or exarate pupa. Other insect groups have functional mandibles that can cut their way out of the pupal cuticle, or adect their way out. These types of pupa are sometimes referred to as adect or exarate.
When it comes to damaging plants, grubs and beetles are the most destructive of all insects. The wormlike, legless larvae of these pests feed on the roots and other underground parts of the plant, causing severe crop damage. Once they reach maturity, the larvae either dig themselves into the soil for a prolonged hibernation or drop to the ground where they create oval pupal cells in the soil.
Adult Stage
The adult stage is the last of four pest stages and the one that usually causes the most damage. Adult insects are easy to spot and can be controlled with targeted insecticides and biological controls. However, interrupting the pest’s life cycle at the egg or larval stage is the best way to control the pest.
Some pests have incomplete life cycles, meaning that they hatch from eggs into nymphs which look similar to the adults and remain in this nymphal stage until they mature into adulthood. Insects with incomplete life cycles include the grasshopper, true bugs (stink bug and squash bug), and cabbage maggots. These insects injure plants by piercing and sucking juices or by chewing leaves and stems.
Other insects have complete life cycles, such as beetles and moths. These lay their eggs either singly or in groups, and the eggs hatch into grubs that feed on the roots, tubers, or leaves of the plant. After reaching maturity, grubs form a protective cocoon, which is called pupa, and the moth or beetle emerges into the adult stage.
These insects injure plants by chewing leaves and stems, sucking juices, or spreading diseases. Some, like the bean leaf beetle, cause significant crop losses. These beetles overwinter in or near crop residue and damage soybeans by feeding on the underside of the leaves, leaving rounded holes. They also attack the pods and may girdle the plant.
Other insects, such as aphids, mites, and gall midges, have complete life cycles and are easier to control than adults. The aphids are especially difficult to control once the populations reach an outbreak level. In addition, the aphids are often more difficult to control during hot and dry weather.
Some insects are perennial pests, meaning that they exist in some locations year after year, such as the plum curculio, flea beetles, and striped cucumber beetles. Others, such as the gypsy moth and cankerworms, have irregular boom and bust patterns. The fluctuations appear to be caused by factors such as weather, competition with other insects, and disease.
