25 July 2026
July is Bug Season. This week they took center stage at Raccoon Wildflower Reserve, Frick Park and Aspinwall Riverfront Park (a.k.a. Allegheny RiverTrail Park).
Butterflies are hard to photograph with my cellphone but I managed to capture images of a pearl crescent at Raccoon Wildflower Reserve.
Looks like a bee but this is a fly — a bee-fly on Queen Anne’s lace at Aspinwall.
I also found evidence of tiny wasps and chased a Great-sized wasp from flower to flower.
At Frick Park we found a red misshapen gall on a blackberry stem. Not only did the gall look like an infection but the stem looked like it had broken at the site of the gall. This is evidence of a blackberry knot gall wasp (Diastrophus nebulosus).
The wasp is a blackberry stem specialist. It doesn’t use other plants.
Inside the gall are the tiny larvae of Diastrophus nebulosus that irritate the plant so much that it produces a big gall. The adults are tiny too — a little smaller than a sesame seed.
On the high end of the size spectrum are great digger wasps. I found a great black digger wasp (Sphex pensylvanicus) at Aspinwall Riverfront Park. Though “Pennsylvania” is in their name these wasps have a wide range in North America.
Like most wasps, great black digger wasps are solitary. The female makes her nest by digging a hole with lateral chambers. To provision the chambers she captures and paralyzes a katydid or grasshopper and then lays an egg on it. When the egg hatches the larva feasts on the paralyzed (live) insect and emerges as a wasp. Read more about it here.
There are other colors of digger wasp. I saw a great golden digger wasp 13 years ago at the Montour Trail. Late July seems to be their favorite time in southwestern PA.
https://en.wikipedia.org/wiki/List_of_taxa_that_use_parthenogenesis
Insects are all females reproduce by parthenogenesis It is important to remeam it
Therefore, they are totally immense populations of females that outperform humans by billions per person, which is usually known as pest species.
Actually parthenogenesis among insects is rare overall. Only one of the 5 insect species in my article uses parthenogenesis — the gall wasp — but the others do not.
Only 1.8% of insect species:
“Parthenogenesis—reproduction from an unfertilized egg—occurs in nearly all or roughly 79% to 100% of insect orders. But while the trait is present across the vast majority of insect orders, it is found in only a tiny fraction of individual insect species (estimated at roughly 1.8% or less of described species overall, though much higher in specific sub-groups or agricultural pests).” — Google AI answer
Parthenogenesis is the reproductive strategy of nearly half of agricultural pests:
“parthenogenetic species comprised 45 per cent (North America) or 48 per cent (Italy) of pest species derived from genera where parthenogenesis occurred, compared with an overall incidence of 10 per cent or 16 per cent in these genera. … Parthenogenetic reproduction may be favoured in agricultural environments when particular clones have a high fitness across multiple generations.” — https://pmc.ncbi.nlm.nih.gov/articles/PMC2603198/
Perhaps our monoculture + pesticide method of agriculture makes it easy for parthenogenetic pests to thrive.