Several types of thrips can have variable body colors within their population, from very pale, to very dark, but they are all still the same species.
We call these “color morphs” in the insect world, and they are quite common among many types of insects, from moths to grasshoppers.
While there are likely genetic factors at play, environmental effects can also influence insect color. It’s been shown that cool temperatures during thrips pupal development can induce a change from light to dark in some species.
Whether this provides the thrips any advantage in the winter is still unclear.
However, this color change often leads to concerned growers sending us samples of “unusual dark thrips” suddenly invading their greenhouses in the winter months.
Given the recent occurrence of new, darker-bodied invasive thrips such as Thrips parvispinus (tropical tobacco thrips) and Thrips setosus (Japanese flower thrips) in North American greenhouses, this concern is understandable.
But unless you have imported in new plant material, or are growing tropical crops or hydrangeas, the dark thrips you are suddenly seeing are most likely just your run-of-the-mill species, but a darker morph. As they say, when you hear hoofbeats, assume horses, not zebras.
Read more at onfloriculture.com