Tuesday 29 September 2015

insects that feed on body after death - visual ideas - practical

Bodies attract two main groups of insects: flies (Diptera) and beetles (Coleoptera).
FLIES are found as eggs, larvae or maggots, pupae, empty pupal cases or as adults.
EGGS are tiny, but usually laid in clumps. They are often found in a wound or natural opening, but
 may be in clothing etc. Eggs are collected with a damp paint brush or forceps. Half are preserved 
in alcohol and half are collected alive. Eggs are especially important when maggots or later insect 
stages are absent. The time of hatching is vital and the eggs must be monitored every few hours.
MAGGOTS are found on or near the remains and may be in large masses. The masses generate 
heat, which speeds up development. The site of the maggot mass, the temperature (and size) of
 each mass are important.  Large maggots are usually older, but small maggots may belong to a 
different species so a range of sizes are collected. Since third instar larvae leave the body to pupate, 
 the soil around the body is carefully sifted. The soil below the corpse is also checked to a depth of  
several centimetres. Half the sample is kept alive and half preserved immediately. Preservation 
allows the entomologist to see what stage the maggots were in when collected. Preserved specimens 
may also be used as evidence in court.
PUPAE and EMPTY PUPAL CASES are very important but easy to miss. Pupae like dry, secure 
areas away from the wet food source so clothing pockets, seams and cuffs are likely hiding places. 
If the remains are found indoors, they may be under clothing or rugs etc. Pupae are dark brown, oval, 
and range in size from 2-20 mm.  Empty pupal cases look  similar, but one end is open where the 
adult fly has emerged. Pupae are not preserved. They won't grow and the species and exact age 
cannot be determined until the adult emerges.
ADULT BLOW FLIES are not as important as eggs, maggots or pupae. They are only used to 
determine the species of insect. However, if an adult fly has crumpled wings, it may have just emerged 
and can be linked directly to the body. These are collected and kept separately. Flies smaller than blow
 flies are important at all stages as they are used when analyzing the succession of insects on the 
remains
BEETLES (Coleoptera) are found as adults, larvae, pupae and as cast skins.
http://www.sfu.museum/forensics/eng/pg_media-media_pg/entomologie-entomology/
All beetle stages are important. They move fast and are often found under the body, or in and under 
clothing. They should be place in alcohol in preserve them.


    OTHER INFORMATION is also important. For the site, this includes:

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