The holly blue butterfly, once in perilous decline, has made a strong comeback with a number increase of more than 100 percent, according to the Guardian. With their fate naturally and unavoidably intertwined with a type of parasitic wasp, the blue butterfly was on a decline cycle for many years.
The parasitic wasps would lay eggs inside the azure bugs, injecting their unborn into them with a sting. Then, the eggs would eventually hatch, killing the blue butterfly as it is born.
The parasites rely entirely on the blue butterfly population to carry its offspring and can rapidly reduce the insect's numbers.
But in 2014, the butterfly count rose by about 151 percent, according to the Butterfly Conservation.
According to their Big Butterfly Count, there is an abundance of 10,334 of the butterflies.
Because of the co-dependent relationship between the two insects, the decline in population for the butterflies negatively affects the parasite's ability to reproduce as well, allowing for a window for the butterfly population to spring up every several years or so, according to the PressReader.
That fact is supported by the years in which the butterfly population has shot up, in 1976, 1984, 1990, 1996 and 2010.