Ageing/sexing criteria Some of the criteria for assessing age are based largely on external examination. Fresh material is always useful for confirming the accuracy of such characters, especially in ringed bats whose age is known. Pesticide analysis At present it is too expensive to do routine chemical analysis of bat tissues to check for pesticide residues and few laboratories can undertake the work. If specimens are ever required fora specific project (and it is obviously a very important subject for enquiry), requests will be made. Specimens will need to be very fresh and sent rapidly to the analyst. If the illegal use of pesticides to poison bats is suspected, the relevant agriculture department should be informed. All the Agriculture Departments have laboratories, which are equipped for pesticide analysis and can investigate such incidents. Incidents in the United Kingdom can be reported on a free telephone line 0800 321 The relevant SNCO should also be informed. Parasites Bats are subject to a variety of endoparasites particularly parasitic worms) and some of the mites associated with bats occur almost internally (e.g. inside nostrils or mouth) and hence can only be collected by dissection of freshly dead or well-preserved specimens others can be missed in searching alive animal. These mites can be treated as for other mites (see Section 5.6), but the endoparasites may need special preservation (e.g. a mixture of glacial acetic acid and alcohol for some worms) and the advice of experts should be sought.