Hemerobius pini © Axel Gruppe
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Hemerobius spp.
(Neuroptera: Hemerobiidae)
Brown Lacewings
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by
K. Fondren
Department of Entomology, Michigan
State University, East Lansing, MI 48823
Brown lacewings may be less commonly observed than the green lacewings (Neuroptera:
Chrysopidae), but they are also important predators of aphids and other small
soft-bodied insects. Most of the Hemerobiidae look superficially alike. The
most common genus occurring in the United States is Hemerobius. The most
common species of Hemerobius is H. stigma (=stigmaterus)
Stephens.
Appearance
Hemerobius stigma is widely distributed across most of North America
and is themost common conifer-inhabiting brown lacewing in most of its range
(Klimaszewski and Kevan 1985). It is relatively large for a brown lacewing (5.0-7.5
mm). The fore wings are narrowly oval with a slightly pointed apex. Color is
a light reddish brown to brownish grey. A close look at the wing venation can
distinguish it from most other Hemerobius species. Species determinations,
however, can only be confirmed by expert examination of the genitalia (Klimaszewski
and Kevan 1985).
H. stigma adult. Photograph courtesy Philip Greenspun
Habitat (Crops)
Typically, brown lacewings become active earlier in the season than green
lacewings. They tend to prefer arboreal habitats such as coniferous and deciduous
forests, plantations, or orchards. Hemerobius stigma is particularly
associated with conifers (Throne 1971)
Pests Attacked
All brown lacewings are voracious predators as both larvae and adults. Prey
includes tree-dwelling insects such as aphids, adelgids and other small soft-bodied
insects. H. stigma is often found in association with the balsam twig
aphid (Mindarus abietinus Koch) in Christmas tree plantations. It is
also an important predator of the balsam woolly adelgid (Adelges piceae)
and pine bark adelgid (Pineus strobi). Laidlaw (1936) recommended
it for control of Cooleyıs spruce gall adelgid (Adelges cooleyi) on
Douglas-fir. It is known to attack a variety of conifer-feeding aphids (McGugan
and Coppel 1962; Laidlaw 1936).
Life Cycle
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H. stigma overwinters as an adult or prepupa (Laidlaw 1936).
It becomes active as early as March in Wisconsin (Throne, 1971) or April
in Quebec (Garland 1981b). Active adults have even been observed in December
and February in British Columbia (Klimaszewski and Kevan 1985). In early
spring, the adults mate and eggs are deposited about two weeks later.
The adult females and the eggs are extremely cold-tolerant (Garland 1981b).
Eggs are laid singly, on fir needles or between bud scales. Eggs hatch
in about 11 days, depending on the temperature (Klimaszewski and Kevan
1985).
Most hemerobiids have three larval instars. All instars are active feeders.
They are relatively slender, with a small head and jaws compared to chrysopid
larvae (see chrysopid page). After the third instar, the larva forms a
pupa in a silk cocoon. The pupal stage lasts about 9-14 days in the summer.
Two generations per year are most common, although temperature can play
a significant role.
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H. pacificus larva. Used with permission from University of California
Statewide IPM Project.
J.K. Clark
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Relative Effectiveness
Hemerobius species have great potential as biological control agents
for several reasons: the adults are long-lived and have a high reproductive
capacity, both larvae and adults have voracious appetites, and their prey includes
many pest species (Klimaszewski and Kevan 1985).
Pesticide Susceptibility
As with most beneficial insects, brown lacewings are susceptible to broad-spectrum
insecticides.
Conservation
Conservation appears to be the best way to encourage populations of brown lacewings
in the field. Avoiding insecticide use when lacewings are present and encouraging
forested windbreaks or trees along field edges may be helpful. Adults are easy
to scout by foliage beating over a sheet --they have a 'drop dead' response
when disturbed and will remain motionless for a short time. Use this scouting
method to determine if lacewings are present and active in early spring.
Commercial Availability
Currently, brown lacewings are not reared commercially. Mass rearing of brown
lacewings is difficult, requiring huge numbers of aphids (Garland 1981a).
References
Garland, J.A. 1981a. Effect of low-temperature storage on oviposition in Hemerobius
stigma Steph. (Neuroptera: Hemerobiidae). Entomol. Mon. Mag. 116: 149-150.
Garland, J.A. 1981b. Observations on survival of eggs of Hemerobius stigma
(Neuroptera: Hemerobiidae) following exposure to frost. Manitoba Ent. 12: 61-62.
Klimaszewski, J. and D.K. McE. Kevan. 1985. The Brown Lacewing Flies of Canada
and Alaska (Neuroptera:Hemerobiidae). Part 1. The Genus Hemerobius Linnaeus:
Systematics, Bionomics and Distribution. Macdonald College, McGill University,
Lyman Entomological Museum and Research Laboratory, Memoir No. 15.Ste Anne de
Bellevue, Quebec.
Laidlaw, W.B.R. 1936. The brown lacewing flies (Hemerobiidae): their importance
as controls of Adelges cooleyi Gillette. Ent. Mon. Mag. 72: 164-174.
McGugan, B.M. and H.C. Coppel. 1962. Biological control of forest insects,
1910-1958. In: A Review of the Bioloigical Control Attempts against Insects
and Weeds in Canada. Tech. Commun. Commonw. Inst. Biol. Contr., Trinidad 2:35-216.
Throne, A.L. 1971. The Neuroptera-Suborder Planipennia of Wisconsin. Part I
--Hemerobiidae, Polystoechotidae and Sigyridae. Mich. Ent. 4: 79-87.
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author (if credited on the page you are using). A recommended form for citing this website is:
Weeden, C.R., A. M. Shelton, and M. P. Hoffman. Biological Control: A Guide to Natural Enemies in North America.
http://www.nysaes.cornell.edu/ent/biocontrol/ accessed (date).
Suggestions, corrections, and/or comments are appreciated: Contact
Tony Shelton (ams5@nysaes.cornell.edu).
http://www.nysaes.cornell.edu/ent/biocontrol/predators/hemerobiid.html
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