Adultarthropod specimens are most frequently submitted to the clinical laboratory for identification; larvae are small and not as easily observed during the patient exam.
Whole specimens submitted to the clinical laboratory may not need to be identified to the genus and species level, depending on the arthropod. (For example, ticks should be identified at the species level, while it is not necessary for bedbugs to be identified at this level.)
Morphologic features are essential in making an identification using:
- Macroscopic observation
- Take measurements (length and width) using a small metric ruler (mm or cm)
- Observe for blood spots or red color inside the translucent abdomen
- Record the types and numbers of body parts seen
- Use of a light microscope (also called an optical microscope) with an illumination source and different levels of magnification; an ocular micrometer is proper if measuring small organisms
- Use of a stereo microscope or dissecting microscope with low power and reflected light from the object
During the macro- and microscopic examinations, ask the following questions:1. Is there a head, thorax, or abdomen? (Count the number of body parts.)
2. How would you describe the abdomen? (Tail present? Pinched waist? Are wings present? Do wings cover the abdomen? Are wings shorter than the abdomen?)
3. Are legs present? (How many pairs of legs?)
4. Do you see a pair of antennae? (How many segments?)
5. How many pairs of wings are present? (Membraneous? Or leathery? Scales? Are the pairs similar or different?)
6. Are the mouthparts visible? (Retracted into the head? Or tubular? Sucking?)
7. Are body segments visible? (Does each segment contain a pair of legs? Or two pairs?)
Table 1. Morphology of Medically Important Arthropods.| Basic ID | Abdomen, Mouth | Legs | Antennae | Wings |
| Scabies, Mites | Tiny, rounded shape. Mouthparts are directed anteriorly. Dorsal spines. Scabies burrows in skin. | 2 pairs anterior, 2 pairs posterior | No actual antennae, but palps and mouthparts/ suckers may be confused with antennae | None |
| Bedbugs, Kissing Bugs | Head, thorax, abdomen; tubular mouth directed backward. | 3 pairs | 1 pair (four-segmented long antennae) | Wings in kissing bugs, but reduced wings or pads in bedbugs |
| Lice | Sucking mouthparts retracted into the head. | Claws attached to each leg; 3 pairs of legs | 1 pair (five segmented) | None |
| Ticks | Head and abdomen; oval body, saclike. | 4 pairs as adults | None | None |
