Fruit fly Procecidochares anthracina
Buckle up! This week’s crawly once again reminds us that nature never runs out of “amazing!” Meet the Procecidochares anthracina fruit fly (we’ll call them “anthra” for short).
Now, don’t panic! This isn’t the type of fruit fly that will go after your bowl of grapes or any of the fruit in your yard. In fact, anthra doesn’t go in for fruit at all. Some other species in their family (Tephritidae) do favor fruit and a few are considered “pests.”
Anthra lay their eggs inside the stems of plants in the goldenrod genus (Solidago). When the eggs hatch and the larvae begin to feed, they form beautiful flower-like galls.
Galls are abnormal growths that occur on leaves, twigs, roots or flowers of plants. They are caused by irritation and/or stimulation of plant cells due to feeding or egg-laying by insects. Galls provide a safe home for the insect, where they can feed and develop. Galls cause cosmetic changes in the host plant, but don’t kill the host plant.
As you can see by the photo, anthra don’t make funky, lumpy galls, but pretty flower-like ones known as “leafy rosettes.” A pretty name for a pretty gall created by a pretty fly. When the galls are small, they resemble miniature pineapples.
Because young anthra feed only on goldenrod species, they’re called “food specialists.” Some other fruit flies go in for various fruits and plants, they’re dubbed “food generalists.”
There are 17 species anthra’s genus, two of whom can be found in Oregon. The best time to see them is in late spring and early summer. They lay the eggs in the base of the stems of emerging goldenrod. If you see telltale “false flower” galls on goldenrod plants, you know anthras have been around.
Enough about galls, lets talk about how drop-dead gorgeous anthras are. Those boldly patterned wings serve one purpose for females and two for males.
Males wave those striking wings around to attract females – sort of a mix of signal flags and a choreographed dance.
Both sexes of anthras use their wings for defense. Anthras have evolved to mimic jumping spiders. The patterns on their wings look like jumping spider legs, and anthra move their bodies and wings to match the warning movements of a jumping spider. Putting a twist on a classic phrase; they are sheep in wolves’ clothing!
Male anthras may also mimic jumping spiders in an attempt to scare other male anthra out of their territory.
If you’d like to see anthra up close and personal, plant some native goldenrod in your yard. Luckily our native species, Western goldenrod AKA Canada goldenrod (Solidago lepida), is a large, showy flower, growing up to five feet in height.
Double bonus, goldenrod blooms in late summer and early autumn when so many other flowers have passed and we’re all longing for some pretty blooms to liven up our gardens.