Grain mites, psocids, and other stored product pests need _________ to build high numbers.

• A. Low humidity
• B. High humidity
• C. High temperature
• D. Low temperature

Answer: (B)

Moisture availability drives their population growth. Grain mites, psocids, and other stored-product pests thrive when relative humidity is high because moisture is essential for their eggs to hatch and for adults and nymphs to survive and reproduce. In humid conditions they also often encounter mold and fungi on stored goods, which provides abundant feeding material and supports rapid population growth. Dry conditions, by contrast, slow or stop their development, so keeping storage areas dry and well-ventilated is a key way to prevent outbreaks. Temperature can influence activity, but humidity is the critical factor that allows these pests to build high numbers.