INTRODUCTION
Since lady is defined as “a woman of good family, social position,
breeding, etc.,” this may refer to the fact that most species
of this beetle family are highly beneficial insects; only 3
of 475
United States
species are not beneficial. Some species have a habit of overwintering in
structures and are therefore nuisance pests. Ladybugs are found worldwide with about 475 species occurring
in the
United States
and
Canada
.
RECOGNITION
Adults about 1/32-3/8” (0.8-10mm) long; shape distinctive, broadly
oval to nearly round, strongly convex dorsally, nearly flat
ventrally. Color red, orange, yellow, brown, or shiny black,
usually with various markings including white spots; often bright
yellow, red or orange with black markings or black with yellow,
orange, or red markings. Head partly to completely concealed from above. Antenna short to usually very
short, 8-11 segmented, with weak
club of 3-6 segments. Tarsi apparently
3-3-3
, actually
4-4-4
(3rd segment minute).
Larvae
look like tiny flat alligators, often with numerous spines and/or
wartlike structures; color usually blackish, some with red,
orange or yellow spots or bands; some species secrete a white
waxy material which makes them resemble mealybugs.
SIMILAR GROUPS
(1) Tortoise beetles (Chrysomelidae) with tarsi appearing
4-4-4
, actually
5-5-5
with minute 4th segment. (2) Handsome fungus beetles (Endomychidae) have
base of pronotum with 2 lengthwise grooves and usually black
with red or orange. (3)
Marsh beetles (Helodidae) with antenna threadlike or sawtoothed
and tarsi
5-5-5
with 4th segment lobed beneath. (4) Shining mold beetles (Phalacridae) with
antennal club distinct, 3-segmented, tarsi apparently
4-4-4
(actually
5-5-5
), and brown or black with no markings. (5) Other similarly shaped beetles (order Coleoptera)
with a distinct antennal club and/or tarsi different.
REPRESENTATIVE SPECIES:
1. Asian
lady beetle, Harmonia
axyridis (Pallas). Adults
typically with pronotum black with wide ivory lateral/side margins
and basal median mark yielding dark M-shaped pattern, elytra
mustard yellow to dark reddish orange, each usually with several
black spots but spots sometimes indistinct or absent; length
about ¼-3/8” (6-10mm); found throughout most of United States
and parts of Canada.
2 Convergent
lady beetle, Hippodamia
Convergens Guerin-Meneville. Adults with head, pronotum, and legs black,
pronotum with a whitish margin and centrally with 2 convergent
whitish lines, elytra red, each with 6 black marks with anterior
3 smaller than posterior 3 but varying to elytral spots almost
absent; length about 1/8-1/4” (4.2-7.3 mm); found throughout
the United States and southern western Canada.
3. Ninespotted
lady beetle, Coccinella
novemnotata Herbst. Adult
with head black with pale band between eyes, pronotum black
with pale yellowish front and side margins, elytra orange to
reddish yellow each with 4 black spots but varying to elytral
spots almost absent, scutellum (triangular piece between elytral
bases) black and black extending into elytra; length about 3/16
– ¼” (4.7-7.0 mm); found throughout the United States except
for coastal North Carolina southward to west Florida peninsula
and from southern Louisiana west through central Texas to southwestern
New Mexico, and in southern Canada but extending far northward
in western Canada.
4. Spotted
lady beetle, Coleomegilla
maculate (DeGeer). Adults
elongate, somewhat flattened; color red or yellowish orange,
head with black margins, pronotum with 2 black spots, and 6
or 7 black spots on each elytron; length about 1/8-3/8” (4-8mm);
found from Ontario through Florida, west to Minnesota and Texas,
and west along the Mexican border through southern California.
5. Twicestabbed
lady beetle, Chilocorus
stigma (Say). Adults
black except pronotal front and side margins, spot on each elytron,
and abdomen red or yellow; length about 1/8-3/16” (3.75-5mm);
found east of the Rocky Mountains and adjacent southern
Canada
.
6. Twospotted
lady beetle, Adalia bipunctata (Linnaeus). Adults typically
with pronotum black with wide ivory lateral/side margins and
basal median mark yielding dark M-shaped pattern, elytra orange,
each with a median black spot; length about 1/8-3/16” (3.5-5.2mm);
found from Labrador, Canada, to Alabama, west through Alaska
and California.
BIOLOGY
The overwintering adults emerge from hibernation and
the orange eggs are laid on end in single or multiple groups
of 12 on plants infested by aphids (plantlice), mealybugs, scale
insects, etc. Larvae pass through 4 molts. Mature larvae attach to leaves by the tip of
their abdomens and pupate without forming a cocoon.
HABITS
Larvae and adults are predaceous on aphids, mealybugs,
mites, scale insects, other soft-bodied insects, and their eggs,
making them very beneficial insects. A few species are leaf feeders and are important plant
pests, for example, the Mexican bean beetle, Epilachna
varivestis Mulsant.
In
the autumn, adults seek protected places in which to overwinter. These may include under leaves, rocks and landscape timbers
but also inhabited structures. Unfortunately, the release and use of lady beetles for
biological control by organic gardeners, the USDA (especially
the Asian lady beetle for control of aphids on pecan trees and
fruit crops), and others has greatly increased the incidence
of their entering structures to overwinter by artificially increasing
their numbers.
CONTROL
Because lady beetles are beneficial and are not of any
health or structural importance, no direct control is recommended. Use of preventative physical barriers aimed
at adults before they congregate and attempt to enter structures
and educating the customer are the best solution.
Physical
barriers involve exclusion. Although total exclusion is probably not possible, all
vents (roof, overhand, weep holes, etc.) should be screened
with at least 16-mesh screening. Caulk (silicone based is recommended) around cable entrances,
windows, (spring-loaded with a cable running through the flue
pipe and a lock-catch in the fireplace) may be advisable. These steps should be taken in June or July.
No
attempt should be made to kill these beetles in wall voids at
any time because dead insect bodies attract dermestid beetles
(larder beetles, carpet beetles, etc.). Dermestid larvae wander and readily enter the
living space, causing numerous complaints. Instead, wait until summer when all live overwintering
adults are out of wall voids. Then follow the outside control measures given above. However, temporary relief is possible by using a vacuum
to remove the beetles, and sealing their entryways into the
living space.
Temporary
but immediate indoor relief can be achieved by vacuuming. To prevent the entry of more adults, seal the possible
routes of entry with paintable silicone caulk and/or expandable
foam. Entry points include around window pulleys (seal
with tape or steel wool), window frames, door frames, baseboards,
etc. For electrical outlets
and switch boxes and heating duct and return-air vents, remove
the coverplate, seal, and replace. For light fixtures and ceiling fans, remove the fixture
to its base plate, seal, and replace. Most species can be harvested with insect light
traps (ILTs) from problem areas such as attics and false-ceiling
voids.