Sending insect specimens for identification
Andras Szito, Taxonomist/curator
Many farmers, gardeners, department staff and members of the public require identification of insects suspected of causing damage to agricultural crops, fruit trees or stock, or unusual insects, spiders and mites. Most of the insects are harmless, or even beneficial to man. For reliable identification the specimens should be undamaged and in an appropriate developmental stage.
Collection
Some of the insects show considerable variation in size, coloration and sculpture. With others, males and females cannot be separated by naked eye and for identification the entomologist needs both sexes. Sometimes the adult form is rare within the population. To overcome these difficulties always send 10-15 specimens.
Make sure that the sample is always freshly collected because some insects deteriorate rapidly. The best means of preservation of specimens before correct killings is to keep the insects alive, therefore do not leave the sample in the car because the animals will die in a few hours.
Collection data
Adequate collection data are essential not only as an aid for the successful identification but also if the entomologist decide to keep the specimens in the Insect Reference Collection. A specimen without collection data is scientifically worthless and will not be kept in the Insect Reference Collection. Collection data should be always written by pencil, or pigment pen. Never use ball point pen, or any other pen.
The absolute minimum of information should be given is:
- Locality: where the specimens were collected
- Date: when the specimens were collected
- Collector: who collected the specimens.
Additional valuable information:
- What plant or animals were they feeding on?
- Description and extent of the damage
- Often it is great help if you attach a damaged plant sample to the insect specimen.
Killing
If the specimens are predators such as ground beetles, or plant feeders with strong jaws such as scarab larvae, it is best to send them dead because they may damage each other.
Most widely used killing agent and preservative is 70% alcohol, or methylated spirit. Both are very good for killing hard-bodied insects. The small beetles, ants, bugs, aphids, thrips, spiders and mites can be killed this way. The great advantage is that it is easy to store and handle.
Water at just below boiling point an excellent killing agent though it is not readily available on the field.
Butterflies and moths should be killed by freezing for 24 hours. In the field it may be impossible, in which case place them in airtight container with a ball of cottonwool, or tissue soaked in nailpolish remover, or acetone. If using these chemicals, use a glass jar for killing otherwise the chemicals may react with plastic. After killing place them gently in a plastic container between layers of facial tissues.
Larvae such as caterpillars, grubs and maggots should be killed by pouring near-boiling water onto them. A few minutes later the specimens should be transferred into 70% alcohol. If the specimens are not boiled first they will turn black in the alcohol and be very difficult to identify. Before killing the larvae, please consult with the entomologist. He/she may decide the specimens should be sent alive for rearing to get the adult stage.
Insects which are attached to their host such as scale insects, mealybugs and lerps, are best sent alive on their host, in a large plastic container. Once the host is dry (be careful not to let the plant become mouldy), the insect will die but we can make perfect microscope slide mounts from them.
There are many more killing methods that are widely used by specialist collectors and suited best to certain insect groups.
Dispatch
Always use the fastest available dispatch service.
Use a strong container/jar wrapped in bubble sheets, or at least send them in padded envelope. Unless you are sending live specimens, they should be sent in 70% alcohol, never in water.
Soil-living animals can be collected and sent in moist soil. The container should be topped up to minimise damage by shaking.
Do not post specimens in the second half of the week because they will likely remain in the post office over the weekend.
Necessary equipment for field officers
- 10x magnifying glass
- Pocketknife
- Insect net
- Round tipped forceps
- Strong, sharp forceps
- Small scissors
- Small (0, or 00) brush
- 20 small 20mL plastic vials
- 10 plastic specimen jars
- 5 cardboard specimen box
- 10 medium-size plastic bags
- 10 medium-size paper bags
- 200mL 70% denaturalised alcohol
- 50mL AGA (for department staff available from Entomology Branch)
- 100mL KAA (for department staff available from Entomology Branch)
- Small pieces of acid-free cardboard
Available from:
Australian Entomological Supplies
PO Box 250
Bangalow NSW 2479
Phone: +61 (0)2 6684 7650
Fax: +61 (0)2 6684 7188