12-7 昆虫侦探（下）（在线收听）

The Bug Detectives

Insects can accurately tell us when someone died. But their lifecycle is crucially affected by one factor above all: temperature. So sometimes, getting them to tell us their secrets is not so straightforward.

Dr. Martin Hall is a Research Entomologist¹ at the Natural History Museum in London. Part of his expertise is determining how crimescene temperature affects the development of our insect witnesses. On a Monday morning in July 1999, Dr. Hall received a telephone call from the Essex police asking him if he could come up and look at a body that they had found in an old ammunition² store. At the time the body was found there had been some tampering³ with the body and it was potentially a murder investigation. There were plenty of flies and maggots on it. The temperature in this underground bunker was very stable so this was in a way similar to the way the type of conditions that they would rear larvae⁴ in the laboratory at a constant temperature. If it had been found outside it would have been much more difficult to estimate the temperatures because of the fluctuations⁵.

Dr. Hall knew he could give the police an answer because the temperature was constant. The murder scene was like a laboratory. Forensic entomology could be completely accurate. There were many different stages of maggots on the body, even eggs as well. Obviously from the point of view of trying to estimate how long the body had been there the biggest maggots were the most useful because these would have been the oldest ones. So the first thing he did when Dr. Hall got the maggots back to the museum: a portion were reared up to confirm the identification and another portion were killed to measure their length and get an estimate of age based on that temperature.

When he measured the maggots and aged them Dr. Hall found out that the oldest ones were about 6 days old. At the time he made this study the police were not aware how long the body had been there, so his evidence was very helpful in pointing the police in what sort of time frame they needed to conduct their investigations.

Forensic entomology tends to be thought of just as maggots and murders, but there are many diverse ways in which insects can help. There was one very important case in which a seizure⁶ of cannabis⁷ was made in New Zealand and with the help of some of the people who work on beetles at the museum, the insects found on the cannabis were identified and a knowledge of their distribution pointed very clearly to Burma or Myanmar, and therefore the accused were faced with a much more serious penalty⁸ for importation of cannabis rather than having grown it locally.

In fact, the research has not reached the end -- there’s plenty more work to do. We would like to see that the development of forensic entomology makes it difficult for people to get away with their murders and of course most murderers like most people have never heard of forensic entomology.

注释：

1. entomologist [7entE5mClEdVist] n. 昆虫学家

2. ammunition [7Amju5niFEn] n. 军火，弹药

3. tamper [5tAmpE(r)] vi. 拨弄，胡乱摆弄

4. larva [5lB:vE] （[复]-vae [-vi:]）n. 幼虫，幼体

5. fluctuation [7flQktju5eiFEn] n. 波动，涨落，起伏

6. seizure [5si:VE(r)] n. 没收，扣押，查封

7. cannabis [5kAnEbis] n. 大麻

8. penalty [5penElti] n. 处罚，刑罚

昆虫侦探（下）

昆虫可以准确地告诉我们一个人死亡的时间。但是它们的生命周期首先受到一个重要因素的决定性影响，那就是温度。所以有些时候，让昆虫告诉我们它们的秘密并非那么简单。

马丁•霍尔博士是伦敦自然历史博物馆的一名昆虫研究专家，他的专长之一就是确定犯罪现场的温度如何影响到昆虫证人的发育。在1999年7月一个星期一的早上，霍尔博士接到了来自埃塞克斯警察局的一个电话，问他是否可以过去一下，看看在一个破旧的军火库里发现的一具尸体。发现尸体的时候，尸体被人动过了，这有可能作为一件谋杀案来调查。尸体上有很多苍蝇和蛆。这个地下军火库内的温度非常稳定，这在某种程度上和实验室内恒温下培育幼虫的条件非常相似。如果尸体是在室外发现的，由于外界存在气温波动，要想估计温度将会困难得多。

霍尔博士知道，由于温度是恒定的，他可以为警方提供一个答案。谋杀现场就像一个实验室。法医昆虫学的结论将会完全准确。尸体上有很多处于不同发育阶段的蛆，甚至还有虫卵。显然，如果想推断出尸体在现场的时间，最大的蛆是最有用处的，因为它们是最老的成员。所以霍尔博士将蛆带回博物馆后，首先做的事情是：把一部分蛆培育起来，以确认鉴定结果；另外一部分被杀死，来测量蛆的长度，并在现场温度的基础上推断出它们的年龄。

在霍尔博士测量蛆的长度并估算其年龄后，他发现最老的蛆的年龄大约是6天。在他进行研究的时候，警方还不知道尸体在现场有多长时间，所以他的证据对警方非常有帮助，为他们指出了他们需要调查的时间范围。

法医昆虫学很容易使人联想到蛆和谋杀案，但实际上昆虫还可以以各种不同的方式为我们提供帮助。在新西兰发生过一件非常重要的案例，警方收缴了一批大麻，在一些研究甲虫的博物馆人员的帮助下，大麻上发现的昆虫被识别，有关它们分布的知识非常清楚地将事发地指向了缅甸。因此，被告不是在当地种植大麻，而是走私进口大麻，他将面临严重得多的惩罚。

事实上，研究还没有到达终点，还有更多的工作需要完成。我们希望看到，法医昆虫学的发展使罪犯很难在谋杀犯罪之后逍遥法外，当然，大部分凶手和大多数人一样，还从来没听说过法医昆虫学。(完)