Yellowjackets are beneficial as they eat many pest species. They may sting when the nest entrance is approached, and can be aggressive, stinging several times.
Paper wasps are beneficial insects. They feed on many insect pests. However, they can and do sting when disturbed, which can be a problem if a nest is touched by someone doing pruning or fruit picking, or if there is a lot of human activity near a nest.
Fleas are the most common transmitter of the rare Bubonic Plague. Their saliva can cause serious Flea Alergy Dermatitus in pets, and reported to cause similar allergic reactions in humans. Fleas can also transfer tapeworms and cause anemia in pets. Flea bites commonly cause painful, itchy red bumps.
Because they nest deep within the hair of animals, these ticks are not immediately apparent. Pet owners typically do not notice an infestation until populations grow considerably large and ticks are visible crawling across floors or walls.