The term PONY PEST is a combination of two words, 'PONY' and 'PEST'. The first word, 'PONY', refers to a small horse, while the second word, 'PEST', refers to an animal or insect that causes damage or annoyance. The crossword solution for this term is HORSEFLY, which is an insect that feeds on the blood of horses and ponies. Horseflies are considered pests because they can cause irritation and discomfort to horses and ponies, as well as transmit diseases.