Subject: Crane Fly?
Geographic location of the bug: Plymouth Meeting Pa
Time: 01:39 PM EDT
Your letter to the bugman: Is this a crane fly? If so what kind of crane fly is this? Are they agricultural pests? They were found mating on my aronia.
How you want your letter signed: Concerned Gardener
Dear Concerned Gardener,
We believe these are mating Tiger Crane Flies in the genus Nephrotoma, which is pictured on BugGuide. According to the Crane Flies of Pennsylvania: “Although individual adults have a relatively short life span of 10 to 15 days, the flight period for each species can last from 25-30 days. The main functions of the adult stage are mating and egg-laying. Feeding is less important, and probably water is the most pressing need.” That said, adults are benign for the gardener, except that they provide food for insect eating birds and other predators that often benefit the garden. The larvae are probably a greater concern since they feed, but according to the Crane Flies of Pennsylvania: “The larvae are found in a wide variety of habitats, varying from strictly aquatic to terrestrial, even relatively dry soil. Their habitats include fresh water in fast-flowing streams, marshes, springs, meadows, seeps, tree holes, algal growth or mosses on rock faces near water, organic mud and decaying vegetable debris along the shores of streams and ponds, accumulated decomposed leaves and rotting wood on the forest floor, and occasionally soil in lawn and pastures. … Larvae are the growth stage and the majority of crane fly larvae are scavengers feeding on decomposing plant material and the associated microorganisms. Larvae of some aquatic species are predators on other small invertebrates, and several are herbivores on algae, moss or herbaceous plants.” There are also many nice images of Tiger Crane Flies on iNaturalist.