Which instar corresponds to 14-16 mm length after 4-5 days?

• A. 1st instar
• B. 2nd instar
• C. 3rd instar
• D. 0th instar

Answer: (C)

Understanding larval development, the growth stages larvae go through are called instars, with each molt signaling a new instar. In blowflies and similar forensic contexts, there are three larval instars before pupation, and each successive stage is noticeably larger than the last. First instar larvae are the smallest, only a few millimeters long. Second instar larvae are bigger, roughly up to about a centimeter. The third instar is the largest larval stage before they molt into the prepupal/pupal forms, commonly reaching around 12–18 mm depending on species and ambient temperature.

A length of 14–16 mm after 4–5 days fits best with the third instar, since that size falls squarely within the range expected for the final larval stage prior to pupation. The zeroeth instar isn’t a standard larval stage in this context, and eggs or newly hatched larvae would be much smaller, so they don’t match this measurement.