Some development data on different species of blowflies (Calliphoridae) and fleshflies (Sarcophagidae)
Life histories of 11 species of blowflies and fleshflies reared at 27 degrees Celsius, and 50 percent relative humidity.
No. of Gen. |
Egg (Hrs) |
First instar (Hrs) |
Second instar (Hrs) |
Third instar (Hrs) |
Prepupa (Hrs) |
Pupa (Days) |
Total Immature (Days) |
|
Sarcophaga cooley |
29 |
— |
24 |
18 |
48 |
96 |
9 |
16 |
Sarcophaga shermani |
28 |
— |
22 |
16 |
48 |
104 |
8 |
14 |
Sarcophaga bullata |
18 |
— |
26 |
18 |
54 |
112 |
12 |
17 |
Phormia regina |
23 |
16 |
18 |
11 |
36 |
84 |
6 |
11 |
Protophormia terranovae |
27 |
15 |
17 |
11 |
34 |
80 |
6 |
11 |
Lucilia sericata |
29 |
18 |
20 |
12 |
40 |
90 |
7 |
12 |
Eucalliphora lilaea |
27 |
22 |
22 |
14 |
36 |
92 |
6 |
13 |
Cynomyopsis cadaverina |
17 |
19 |
20 |
16 |
72 |
96 |
9 |
18 |
Calliphora vomitoria |
5 |
26 |
24 |
48 |
60 |
360 |
14 |
23 |
Calliphora vicina |
5 |
24 |
24 |
20 |
48 |
128 |
11 |
18 |
Calliphora terranovae |
4 |
25 |
28 |
22 |
44 |
144 |
12 |
20 |
(After Kamal, 1958)
(taken from http://folk.uio.no/mostarke/forens_ent/tables_development.html)
The life cycle of flies come in five stages. The first is the eggs. Second, are three instar stages, each resulting in a larger maggot. The fourth is the pre-pupal stage in which the maggot leaves the body and seeks an area to encase itself where it will pupate and become an adult fly. The pupation stage is the fifth and final stage. In the third instar stage the maggot does not completely shed the skin. It retains this skin around the body. This skin is what will become the pupal case (Stoerkay, 2000)(Goff, 2000)(Saferstein, 2004).
The three instar stages are identifiable by the morphology of the mouth parts and posterior spiracles. (Bryd and Castner 2001)
When live maggots are found the investigator may collect sample an compare the measurements with known growth rates (Stoerkay 2000). However, growth rates are affected by both environmental conditions and the species of fly. This method should be used in conjunction with laboratory rearing.
The Bloated Stage
The bloated stage is distinguished by the production of gases caused by bacterial break down of the tissue. The eggs of the flies will have hatched by this stage. The maggots will be actively feeding which also contributes to decomposition. The feeding activities of fly maggots speed the breakdown of tissue. Feeding activity also raises the temperature of the body. The higher the temperature of the body the more bacterial activity occurs. Maggots predigest their food. They use saliva to digest flesh and then suck up the liquid just as adult flies do (Goff, 2000). As a mass they are more effective than alone and tend to move in masses. The action of both bacteria and maggots can raise the temperature of the body as high as “127 degrees Fahrenheit.”(Goff,2000, p. 45).
This raising of the body temperature has a significant result for those researchers working in temperate to cold climates. If the body has reached this stage before the frost maggots may survive in temperatures lower than usually associated with maggot activity. The maggots will retreat to the inside of the body consuming it from the inside. By doing this they protect themselves from freezing temperatures. Maggots may continue to develop past where low temperatures would normally arrest development. Thus, a body found in the spring with a shell of skin but no internal structures was probably in the bloated stage in the late fall(Erzinclioglu, 2000).
Other species found on a body at this stage are Histor beetles (Histerade), Rove beetles (Staphylinidae) and burying beetles(Silphidae). As well, predatory wasps and ants may be present(Goff, 2000).
The Decay Stage
In the decay stage the skin has ruptured and body fluids permeate the surrounding area. Maggots stop feeding and move off of the body. The maggots are in the third instar stage during this phase. The maggots will move off of the body as a mass or individually according to species (Bryd, 2001)(Goff, 2000). Some will move as far away as 20 feet away from a body (Goff, 2000). The surrounding area around any remains in this stage should be searched for maggot masses under carpets and ground cover. Beetles become the most common insect at the end of this stage(Goff, 2000).