**9.1 Decomposition: fly life cycle and development times**

Marine Diptera, which perform decomposers function are land-dwelling muscoid flies, for instance, in aquatic habitations, Calliphoridae are underrepresented mainly when a carcass is fully underwater. Corpses floating on surface of water and alongside shorelines, deal a terrestrial-aquatic boundary, which is expected to comprise dipteran agents of both surroundings. Certain ephydrids of shore-inhabiting devour minor carcasses of animals on seashores, suggestive of their legal prospective to as well practice bigger carcasses. Forensic circumstances in water linking to a deceased person normally feature presence of chironomids, their abundance, diversity, ubiquity and species-specific appearances, which make to Chironomidae possibly beneficial in criminal inquiries. Adhoc examples to utilizes marine Diptera in legal inquiries have been recognized. Exuviae of black fly *Prosimulium fuscum* (Syme & Davies) (**Figure 6**) pupae found on a submerged case helped to convict a murderer by countering his purported timeline of events [48].

Forensic entomology creates use of information resulting from either the series of arthropods on animal carcasses or human corpses or temperature-dependent development of insects (principally flies) to appraise the time gone since passing away or postmortem interval (PMI) or estimate of the time between death and corpse detection. Flies are the most significant organisms for forensic study and especially valuable in determining the age of corpse from duration of a few hours to a few years [49].

The occurrence of insects within any carcass is a serious sign toward guessing death time of bodies deceased for lengthier time periods. Since, flies quickly find out a body and their times of growth are foreseeable during specific ecological circumstances, so death time may be determined by calculating back days from the state of fly's growth existing on carcass.

**Figure 6.** *Black fly.*


Habitually, tropical marine insects constantly are newcomer and have shortage of synchronized cohorts. In short-lived, summer-dry system, certain larvae of flies

Non-feeding and shortened adult life is characterized in Deuterophlebiidae, Nymphomyiidae and many Chironomidae. Deuterophlebiids have the shortest adult lifespan than any Diptera, with females living for a few hours and males possibly 30–45 min. A short-lived, and nonfeeding imaginal phase would be adaptive anywhere larvae get means for gamete making or where ecological conditions

Most flies remain active throughout the year and many of them live less than a year. Many fly species survive the winter only as eggs. Others survive as pupae and a few survive as larvae or adults. Like all insects, they do not truly hibernate, but enter a state of diapause, which slows down their development and appetite, until temperatures rise and they become active again. Unless they hibernate, adult flies do not usually live very long, often only a month or two and sometimes just few days or weeks. Flies usually spend most of their lives as a larva or a pupa, and mostly spend the winter as adults in cracks and openings, and become active in spring. Flies are eaten by many predators, so very few of them live as long

Diptera has worldwide distribution, diverse habitats and diets in both larvae as well as adults, while sizes range 1 mm–7.5 cm. Among differentiating taxonomic structures, wings are utmost distinct feature of Diptera, and these comprise a couple of functional front wings and condensed rear wings termed as halteres that help as balancing organs. With the exception of male scale insects, Diptera only have hind wings adapted into halteres. The thorax contains a complete mesothorax occupied with muscles that operate to forewings. The single couple of wings as well differentiate to Diptera from other insects so-called flies (dragonflies, caddisflies), whereas the posterior halteres isolate Diptera from other insects having single pair

Separation of Diptera into suborders is established on wing venation and structure of antennae. Additional key features are chaetotaxy and arrangement of strong bristles in several fixed locations, and given specific or group names. Split-up of Diptera into families is based on habits (feeding), and habitats of adults and larvae. Species and genera are differentiated by details of head structure and profile of head, degree of separation and shape of eyes, and legs shape and proportions of segments. Abdominal shape generally defines distinctive appearance of a genus, however it is hard to express because the shape differs as the insect is starving, well

Diptera order is traditionally divided into two suborders distinguished by the differences in antennae, Nematocera (flies with multi-segmented antennae) and Brachycera (flies with stylate antennae) having about 110 families divided between them although one suborder Cyclorrhapha is non-monophyletic (flies with aristate

The Nematocera species are recognized by their elongated bodies and manysegmented, often feathery antennae as represented by mosquitoes and crane flies.

diapause in hyporheic sediments till surface movement proceeds.

*Typical Flies: Natural History, Lifestyle and Diversity of Diptera*

unfavorably affect adult persistence [52].

*DOI: http://dx.doi.org/10.5772/intechopen.91391*

**11. Life of Diptera**

as they can.

antennae) [54].

**19**

**12. Classification of Diptera**

of wings (certain beetles and mayflies).

fed or gravid (viviparous flies, for instance, tsetse fly) [53].

**Table 1.**

*An average approximate development times (in hours) of some specific fly species at 20°C.*

Blow flies (family Calliphoridae) are metallic blue, green or black in color, noisy in flight and resemble to the housefly. A female of blowfly at one time lays up to 300 eggs and with many females visiting any corpse, number of maggots may be immense. For instance, on a 156 g piece of meat, 48,562 maggots are initiated after 24 hours exposure. On the other hand, since this has been inadequate food to withstand them, only 231 flies lastly emerged. In hot weather, helpful to fly growth, maggots can devour 60% of a human body in less than a week.

The growth times of fly vary depending on the species and the temperature, but generalized life cycle typically takes 3–4 weeks depending on the species. Eggs are found in clusters of up to 300 and time takes 1 day from laying to hatching. Initially, first instar larva feeds on fluid oozed from body then migrates into body and takes 1 day from hatching to first molt. Larva of second instar travels around in maggot mass and from first molt to second molt takes 1 day. Larva in third instar moves still in mass, significantly increases in dimension and takes 2 days from second molt to pre-pupa. Pre-pupa drifts away from the corpse for seeking an appropriate pupation location (commonly in soil), does not forage, converts into pupa and takes 4 days from pre-pupa to pupa. Pupa exist within puparium, does not feed and transformation from pupa to adult fly emergence takes 10 days. Upon emergence from pupa, adults fly mate, feed on protein from body fluids, and lay eggs on corpse and emergence to egg laying takes 2 days [50, 51]. The life table (**Table 1**), shows an estimated development times (in hours) at 20°C of certain fly species.

### **10. Phenology**

A characteristic life-cycle of dipteran follows a short-term egg stage (generally days or on occasion greatly longer), larval and pupal phases of variable length, and an adult stage lasting for a few to many hours or days. The period of larvula is shortest, while the last larval stage that is key feeding form is much lengthier. Totally, larval instars share an identical habitat, however various Chironomidae make sure to have planktonic larvulae and benthic later-instars. A lot of marine Diptera is univoltine categorized by quick development. In cyclical system with cold season, immature insects generally in an initial instar, diapause till environments are satisfactory. Postdiapause development regularly initiates with increasing spring hotness, even though algal accessibility and photoperiod may be associated. Period after egg-hatch to adult beginning differs among and occasionally contained by species, such as does presence of further generations (bivoltine to multivoltine). *Typical Flies: Natural History, Lifestyle and Diversity of Diptera DOI: http://dx.doi.org/10.5772/intechopen.91391*

Habitually, tropical marine insects constantly are newcomer and have shortage of synchronized cohorts. In short-lived, summer-dry system, certain larvae of flies diapause in hyporheic sediments till surface movement proceeds.

Non-feeding and shortened adult life is characterized in Deuterophlebiidae, Nymphomyiidae and many Chironomidae. Deuterophlebiids have the shortest adult lifespan than any Diptera, with females living for a few hours and males possibly 30–45 min. A short-lived, and nonfeeding imaginal phase would be adaptive anywhere larvae get means for gamete making or where ecological conditions unfavorably affect adult persistence [52].
