3. Ecological Categories Insect activity at a dead body can bedivided into four major categories matching the ecological rolethey play. Some insects are attracted to a dead body and use thebody as a source of food. Other insects are attracted to a deadbody to feed on the first group, the insects that are using thebody for food. \"It's a bug-eat-bug-word, out there!\" And someinsects are attracted to a dead body to use as an extension oftheir habitat. Below are examples of each. (The links includeddirect you to optional BugGuide pages where you can read more aboutthe insect groups.) 1. Necrophagous species: (the word necrophagousis from nekros, from the Greek meaning dead, and phagein, meaningto devour). Necrophagous insects feed on the body and are the mostimportant species in establishing time of death because insectsthat find and use a dead body as a source of food arrive in apredictable sequence based on the state of decomposition of thebody. These insects are referred to as indicator species. Examples:o Blow flies (Diptera: Calliphoridae) are metallic blue or greenflies slightly larger than a house fly. They are also known asbottle flies. They are attracted to the odors of decay and may finda dead body within hours. The female fly deposits masses of eggsaround body openings and the eggs hatch within 24 hours. The larvaefeed on dead animal tissue though at times are found dung, andsimilar materials. When fully grown the larvae pupate on the bodyor in the soil under and around the body. Newly emerged adult flieswill not return to the body to lay more eggs. o Flesh flies(Diptera: Sarcophagidae) are medium-sized and resemble the blowflies and house flies. Flesh flies are dull colored with black andgray stripes on the thorax and checkering on the abdomen. The fleshflies show up on a dead body slightly later than the blow flies.Flesh flies do not lay eggs. Instead the females deposit firstinstar larvae that were hatched internally, directly on the body. oHouse flies (Diptera: Muscidae) do not show up until the body is inadvanced stages of decomposition. o Carrion or burying beetle(Coleoptera: Silphidae) adults may feed on decaying animal tissue,though their larvae feed on the fly maggots feeding on deadanimals. They are therefore slight later to arrive on the scenethan are the flies. o The larvae of carpet beetles and larderbeetles (Coleoptera: Dermestidae) feed on dried organic material,including carrion. 2. Predators and parasites of the necrophagousspecies mentioned above are the second most important group inforensic entomology. These arrive after the first wave iswellestablished. Examples: o The larvae and adults of buryingbeetles (already mentioned) consume flesh, but also eat fly larvaefound in the carcass. o Rove beetles (Coleoptera: Staphylinidae)prey on maggots that are feeding within carrion. 3. Omnivorousspecies: wasps, ants, and some beetles feed both on the corpse andits inhabitants 4. Adventive species: use the corpse as anextension of their environment, that is, primarily a place to hide.o Collembola- springtails o Spiders In some situations, based uponan understanding of the life cycle, habits and biology of thesecarrion-associated insects, the presence of particular species canprovide not only clues to the time of death, but also to thegeneral location of death (e.g. city vs. rural areas) and possiblywhether the person died inside a building or outdoors. These cluesare based upon the biological and ecological characteristics of aparticular species; their life cycles, and seasonal andgeographical occurrence.

The rate of development (that is, growth) of blow fly and fleshfly larvae is variable but predictable, which allows them to beused to estimate time since death. How are the age ofmaggots collected by a forensic entomologist at the scene, thesurrounding environmental conditions, and the postmortem intervalconnected? This is supposed to be an easy question, evenif awkwardly worded. Don't make it harder than it is. What externalfactor determines how quickly or slowly a maggot grows andtherefore the age and the size of collected maggots?