The Post-Decay stage
In the Post-Decay stage beetles are the most prominent order found on a body. The species will vary according to the conditions. Some beetles will not feed in wet conditions while others require wet conditions (Goff, 2000).
The Skeletal Stage
In this stage only soil dwelling insects exist. At this stage it in important to take soil samples from under the body and in the immediate area up to 3 feet from the body (Baden and Roach, 2001).
The following is a short description of the proper methods for collection of insect evidence.
The first step in any investigation is to secure the scene. Once this is done the scene should be documented with sketches, notes and photographs Byrd, 2001)(Saferstein, 2004). The initial investigation for insect evidence should be done by stand still and observing the insect activity around the body. Notes, as to the type and location of insects in the area should be made(Haskell, Lord and Byrd, 2001). By approaching the scene carefully the investigator can avoid scaring away those species which will flee from human disturbance around the body.
Before the body is disturbed the investigator should perform 5-6 sweeps of the area around and above the body using a large insect net(Haskell,Lord and Bryd, 2001). The insects collected can be killed onsite and preserved for later identification(Bryd, 2001).
Once the insects around the scene have been noted and sampled the temperatures in and around the body should be recorded. Typically the ambient temperature, the temperature at the surface,the temperature under the body and an internal temperature are taken. The temperature of and maggot masses present should also be taken(Haskell,Lord and Byrd, 2001).
Once the body is removed the soil temperature under it should be taken(Haskell,Lord and Bryd, 2001).
Finally, meteorological data should be obtained for the area. Soil Samples should be taken under and up to three feet from the body. Peak high and low temperatures should be sampled over several days in the exact location of the body(Haskell,Lord and Byrd 2001).
Once the temperatures have been record the insects on the body can be examined and samples taken. Samples of eggs and larvae from flies can be collected put into 75% ethyl acetate and then fixed an 80% ethyl alcohol(Haskell,Lord and Bryd, 2001)
Live sample of larvae at various stages can be collected and stored for transport in sandwich bags or aluminum foil pouches filled with sand or vermiculite(Haskell, Lord and Bryd 2001). Care should be taken not to use commercially available potting soil or play sand both of which contain insecticides.
Live samples can be raised in a small aquarium with a temperature control of some sort. The maggots themselves can be kept in a low sided dish with beef liver as a food source. Cotton balls soaked in water can be provided as a source of water. The aquarium should have a base of sandy material for the maggots to burrow in during the pre-pupal stage(Haskell,Lord and Byrd 2001).