Scymnus (Pullus) coniferarum Crotch 1874 (Coleoptera: Coccinellidae)
An Adelgid Predator Native to the Western United States
Michael E. Mongtomery1, Richard McDonald2, Laura Schwartzberg3
1US Forest Service, Northern Research Station, Hamden, CT; 2Symbiont, Sugar Grove, NC; 3South Salem, NY
Scymnus coniferarum was previously collected from several western U.S. states and from
British Columbia (Fig. 4). The majority of collections were in California.
Figure 4. Collection records of Scymnus
(P.) coniferarum based on museum
specimens; shaded = general area of
many collections with dots showing
peripheral localities (from Gordon 1985);
red rectangle is area of recent collections
in the Seattle area by the authors.
Since it has been found in northern Idaho and southern Arizona, its climate range seems to
Figure 1. Scymnus (Pullus) coniferarum. Photo by Nathan Havill.
The type specimens collected in 1874 were from pine and an unpublished thesis by
Whitehead stated that large numbers of S. coniferarum were collected from lodgepole pine
and Monterey pine infested with woolly adelgid.
The extensive survey for predators on hemlock by Kohler (2007) found only a single
The conifer lady beetle, Scymnus coniferarum Crotch, is widely specimen of S. coniferarum. We collected S. coniferarum from western hemlock, Tsuga
distributed in the western United States. We have collected more than heterophylla infested with Adelges tsugae (Table 1). We also sampled fir and western white
200 specimens in the Seattle, Washington, metropolitan region from pine infested with S. coniferarum, but did not recover this lady beetle. Its distribution among
adelgid infested hemlock. We have established a laboratory colony and trees is patchy, with trees in locations exposed to direct sunlight favored.
reared it through a complete generation on the hemlock woolly adelgid.
Its biology and host range are being evaluated to assess its potential
for biological control of Adelges tsugae in the eastern United States.
Table 1. Relative number of Laricobius nigrinus (Ln) and Scymnus coniferarum (Scw) collected from
western hemlock in the Seattle, Washington, metropolitan area.
Date Site Ln Scw
26-Feb-08 Ft. Lawton 131 40
The lady beetle genus Scymnus has more than one hundred species
in the United States, with the majority in the subgenus Pullus. These 04-Apr-08 Chittenden Locks 73 36
are small in size, usually less than 3.0 mm with pubescence on the
dorsal surface, antennae 11-segmented, and an incomplete postcoxal 10-May-08 Washington Park Arboretum 10
line. Scymnus (Pullus) coniferarum Crotch (Fig. 1) can be
distinguished from the other native lady beetles in the subgenus 11-May-08 Chittenden Locks 24
Pullus by its more elongate shape (length 1.75 mm, width 1.15 mm)
and distinctive coloration consisting of black pronotum with antero- 11-May-08 Washington Park Arboretum 9
lateral angles yellowish brown and a yellowish brown elytron with
base, triangular area at scutellum and suture piceous (Gordon 1976). 16-Oct-08 Discovery Park 57 12
19-Oct-08 Washington Park Arboretum 188 2
Its coloration closely resembles
Scymnus (Pullus) suturalis 21-Oct-08 Firecrest 150 1
Thunberg (Fig. 2), an introduced
species established in the eastern 22-Oct-08 Salt Hood, Seattle 320 1
U.S.), but the latter is less elongate
and the punctures on the elytron are 23-Oct-08 Marymoor, Bellevue 214 1
coarser, separated by slightly less
than the diameter of a puncture 23 –Oct-08 Ft. Lawton 100 8
23-Oct-08 Discovery Park 45 1
Figure 2. Scymnus (Pullus) suturalis.
Photo by I. Altman 26-Oct-08 Seig Hall, University of Washington 115 2
The shape of the male genitalia is a primary character that 15-Nov-08 Ft. Lawton 30 42
taxonomists use to identify Scymnus species and the sipho
can be used to readily distinguish these two species (Fig. 3). Total 1423 173
Scymnus coniferarum has been relatively easy to rear in the laboratory. At temperatures from 12
to 20° C, it reproduced when A. tsugae on T. canadensis was its food source. The immatures
completed development in 34 days on A. tsugae. Adults ate a mean of 8.6 eggs, 2.8 nymphs,
and 1.0 adults/24 hr. Oviposition by the females was very sensitive to food quality; those
receiving only A. tsugae nymphs did not oviposit. Currently, an F-2 generation is being
produced in the laboratory. Its biology, feeding on both pine and hemlock adelgids, are similar
Figure 3. Male genitalia of Scymnus (Pullus) coniferarum and S. (P.)
to S. suturalis (Montgomery and Lyon 1996).
suturalis; (a, b = genitalia; c, d = sipho).
Crotch, GR. 1873. Revision of the Coccinellidae of the United States. Trans. Am. Entomol. Soc. (Phila.) 4: 363-382.
Gordon, RD. 1976. The Scymnini (Coleoptera: Coccinellidae) of the United States and Canada: Key to genera and revision of Scymnus, Nephus, and Diomus. Bull. Buffalo Soc. Nat. Sci. 28: 1-71.
Gordon, RD. 1985. The Coccinellidae (Coleoptera) of America North of Mexico. J. New York Entomol. Soc. 93: 1-912.
Kohler, GR. 2007. Predators associated with hemlock woolly adelgid (Hemiptera: Adelgidae) infested western hemlock in the Pacific Northwest; 121 pages, Dept. Forest Sci., Oregon State Unviersity
Montgomery, ME, Lyon, SM. 1996. Natural enemies of adelgids in North America: Their prospect for biological control of Adelges tsugae (Homoptera: Adelgidae), pp. 89-102. In SM Salom, TC Tigner, RC Reardon (eds.). Proceedings of the
First Hemlock Woolly Adelgid Review, Charlottesville, VA, Oct. 12, 1995. USDA Forest Service, FHTET,Morgantown, WV.