Sphex pensylvanicus

Linnaeus, 1763

Great Black Wasp, Great Black Digger Wasp

Sphex pensylvanicus is a large, solitary digger to North America. Females construct underground burrows and provision them with paralyzed , primarily , for their . feed on nectar from diverse flowering plants and serve as . The exhibits protandry, with males emerging before females in the breeding season. Despite their formidable size and appearance, they are not aggressive toward humans and only when handled.

Sphex pensylvanicus by no rights reserved, uploaded by jeffcherry. Used under a CC0 license.

Sphex pensylvanicus by (c) Christian Back, some rights reserved (CC BY), uploaded by Christian Back. Used under a CC-BY license.

Sphex pensylvanicus P1280240a by
xpda. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Sphex pensylvanicus: //sfɛks pɛnˌsɪlˈvɛɪnɪkəs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from similar large black by combination of: entirely black body without colored markings; -iridescent smoky ; large size exceeding 25 mm in females; and ground-nesting with . Blue Mud Dauber (Chalybion californicum) is smaller, metallic blue-black, and builds mud nests rather than digging burrows. Great Golden Digger Wasp (Sphex ichneumoneus) has golden thoracic and reddish abdominal . Palmodes and Prionyx wasps differ in abdominal shape and facial markings.

Images

Habitat

Open with soft, workable soil for nesting: forest edges, deciduous woodlands, sumac thickets, gardens, fields with scattered trees, and dirt floors of abandoned structures. Requires proximity to flowering plants for nectar feeding and to for . Often found nesting in where soil conditions permit.

Distribution

Most of the contiguous United States and northern Mexico; range expanded northward to New York, Quebec, and Ontario during late 20th century. Absent from Pacific Northwest and most of Arizona. Western limit reaches southern California.

Seasonality

active in summer months; males emerge before females (protandry). In Iowa study, activity documented from early season through late summer. likely overwinter in pre-pupal state, pupating the following spring and emerging in summer.

Diet

feed on nectar from flowers including (Asclepias syriaca, A. incarnata), mountain mint (Pycnanthemum virginianum), thoroughworts (Eupatorium), buttonbush (Cephalanthus occidentalis), rattlesnake master (Eryngium yuccifolium), sweet clover (Melilotus albus), goldenrod (Solidago), and wild . consume paralyzed , primarily of Microcentrum, Amblycorypha, and Scudderia.

Host Associations

Microcentrum rhombifolium - Greater Angle- , primary item
Microcentrum retinerve - Lesser Angle-
Scudderia furcata - Fork-tailed Bush
Amblycorypha - of
Passer domesticus - House Sparrow steals paralyzed from foraging females
Dumetella carolinensis - Gray Catbird steals paralyzed
Paraxenos westwoodi - causing abdominal deformities

Life Cycle

Female excavates angled burrow 1 inch in diameter and over 1 foot deep in soft soil, creating multiple . Each cell receives 2–6 paralyzed ; single (5–6 mm × 1 mm) glued to underside of first item between leg pairs. feeds for approximately 10 days, reaching 30–35 mm long by 7–10 mm wide before pre-. Likely overwinters as pre-, pupates following spring, emerges in summer. Single per year.

Behavior

Solitary but females may nest in loose . Female hunts , paralyzing each with three (neck once, twice); remains alive for weeks. Prey transported by or dragging to nest entrance, dropped while burrow is inspected, then retrieved and pulled -first into . Nest entrance left open during foraging. Males exhibit territorial and may sleep in clusters. Females vulnerable to kleptoparasitism by birds during prey transport; up to one-third of foraging trips may result in prey loss.

Ecological Role

Important of and other flowering plants. control agent for and related . for avian . for . Serves as bioindicator of healthy, undisturbed soil suitable for nesting.

Human Relevance

Generally : pollinates garden and plants, controls . Not aggressive; rare and occur only when is handled or trapped against skin. Sting reported as painful but not swelling. Historical significance as subject of first article by native-born North naturalist (John Bartram, 1749). May cause concern due to large size and nesting near human structures, but poses minimal actual threat.

Similar Taxa

Sphex ichneumoneusSimilar size and habits, but distinguished by golden thoracic , red-and-black banded , and
Chalybion californicum Mud Dauber is smaller, metallic blue-black, builds mud nests rather than digging burrows, preys on not
Palmodes speciesSimilar western digger but differ in abdominal shape and lack iridescence
Prionyx speciesSimilar size and black-and-red coloration in some, but have silvery on and and different abdominal shape

Misconceptions

Often mistaken for aggressive due to size and black coloration; actually solitary and non-aggressive. Confused with tarantula hawks (Pepsis) by lay observers. Nesting sometimes interpreted as 'colonies' suggesting social ; females are merely exploiting suitable localized nesting substrate. Large size leads to exaggerated fear disproportionate to actual risk.

More Details

Historical significance

First subject of scientific writing by -born North naturalist; John Bartram's observations presented to Royal Society in 1749, described by in 1763.

Foraging efficiency

Remarkably efficient hunters; one study documented 252 collected by an in five days, averaging nearly 17 katydids per female per day.

Nesting substrate

Shows flexibility in nest site selection, using natural soil, dirt floors of abandoned buildings, and even loose gravel or millings.