New backyard bug: Pimpla marginella


Wasps come in all shapes and sizes, from the frighteningly large (and frighteningly named) cicada killer, to the tiny fig wasps, so small you need a microscope to see them. Mud daubers and paper wasps are fairly large, easy to see, as are the yellow jackets that chase after the garbage at the picnic site. But in my back yard, I can see one of the more interesting little wasps, Pimpla marginella, less than 1/2 an inch long but memorably attired with a thorax and legs in stunning red and an abdomen in jailbird black-and-white stripes:

It’s so small that it’s usually overlooked, and for this reason, it hasn’t acquired a common name, but it certainly can be common around here. One morning as I was shepherding Daniel around the back yard, I saw maybe 7 or 8 of them cruising through the grass in one particular corner of the yard. I’m not sure whether they were nesting there (I assume them to be solitary wasps that nest near each other) or whether they were all pursuing prey items that were nesting there (I’m not even sure what they eat, or what hosts these parasitoids use), or what.

Etymology: according to the New Century Dictionary, Pimpla (more commonly Pimplea) was a city and fountain in Greece (in Pieria), sacred to the Muses. In a separate entry, it describes “A genus of pupivorous hymenopterous insects of the family Ichneumonidæ typical of a subfamily Pimplinæ.” The specific name, marginella, is the diminutive form of the Latin margo (margin-), edge, border. I assume it refers to the stripes on the abdomen. It was named by Gaspard Auguste Brullé in 1846.

There isn’t a whole lot of information on the web about this species; this link is the best information I could find, and it’s not much. From there I was able to find a Bulletin (216, 2) of the United States National Museum, that gives this info (spelling mistakes from the copy at

Pimpla marginella Brullé, 1846, in Lepeletier, Histoire naturelle des insects,
hymenopteres, vol. 4, p. 107; 9 . Type: 9 , Cuba (Paris). 

Front wing 4.5 to 8.0 mm. long; temple short, in a medium-sized
female its profile about 0.4 as long as eye in profile; cheek short, in a
medium-sized female about 0.85 as long as basal width of mandible;
metapleurum with dense small punctures and hairs posteriorly and in
its upper front corner, with moderately dense small punctures and
hairs along its upper edge, the rest of its surface smooth and hairless. 

Fulvoferruginous. Pedicel reddish brown; flagellum brown, reddish
brown basally; palpi brown; extreme hind corner of pronotum white;
tegula white, its apical 0.5 ± dark brown; pleura tinged with white next
to coxal attachments; first seven tergites black with an apical broad
white band, the basal half of first tergite more or less ferruginous;
abdomen of male blackish beyond seventh tergite, of female fulvo-
ferruginous beyond sixth tergite, except for the apical white band on
seventh tergite. 

Specimens: 2 c?, 9, Paradise Key, Fla., Apr. 9 and 12, 1951, H. and
M. Townes (Townes). d", 39, Matheson Hammock, Fla., Apr. 9 and
11, 1951, H. and M. Townes (Townes). Also: 13 <? , 119, from Cuba,
Haiti, and Puerto Rico. Our collections were from the undergrowth
of the mixed hardwood forests known in Florida as "hammock." 

This species occurs in southern Florida and the West Indies.

Here’s one last picture; the eyes in bright baby blue are captivating (too bad I couldn’t get a good picture, but these wasps are in CONSTANT motion):