What is a limitation of using flea traps and ultrasonic devices?

In the context of flea control, using traps and ultrasonic devices presents specific limitations, particularly regarding how effectively they address the flea population. The correct answer highlights that these methods typically capture only adult fleas. This is significant because while adult fleas can be effectively trapped and removed, they represent only a part of the flea life cycle. A large number of fleas are in the egg or pupal stages, which are not addressed by these traps. Therefore, reliance solely on these devices can result in a persistent infestation as the eggs hatch and new adult fleas emerge. This limitation underscores the need for a comprehensive treatment approach that includes addressing all life stages of fleas, using methods such as insect growth regulators, along with environmental sanitation and regular vacuuming.

The other options point out potential issues, but they do not relate as directly to the fundamental effectiveness of flea traps and ultrasonic devices in controlling flea populations. For instance, the concern about cost may not be universally applicable, as these devices can vary widely in price. The option regarding the risk of explosions or fires is more relevant to specific types of devices rather than being a general limitation of flea traps or ultrasonic devices. Lastly, while maintenance can be a factor, it is typically not the most critical limitation in terms of directly impacting their