In order to determine the nature and distribution of the nuisance problem in Ohio, we conducted a statewide survey during the summer of 2001. The survey results helped to delineate typical characteristics of homes that are infested by H. axyridis. The average type of house was 73 years old, two-story, wood or vinyl sided and has lots of trees on at least three sides. The colors of the house and roof were not found to be a determining factor for an infestation problem. The data were also used to map the progression of the infestation problem throughout the state over the past decade. The data showed that the problem originated in eastern and southern Ohio and has spread north and west through much of the state in the past decade. The results also gave the relative severity of the problems associated with an infestation. The most irritating problems associated with a H. axyridis infestation are the foul odors the beetles emit and the stains resulting from their hemolymph when they reflex bleed. However, biting and food contamination are also significant concerns. An associated health problem is emerging as evidenced by the 13% of the respondents reporting dermal or respiratory allergic reaction to the beetles.
The survey participants were also asked to provide the date in the fall of
2001 when the beetles first arrive in significant numbers at their home. This information was then graphed with
local weather data to derive predictive events for the arrival of H. axyridis in any given locale. It
appears that H. axyridis are prompted
to search for overwintering sites on the first day over 18°C after a significant drop in
temperature, usually to near freezing. Some survey participants also tracked the
management methods used throughout the period of infestation in the fall of
2001. This data was used to develop case study reports on the efficacy of the
different management techniques.
Problems with H. axyridis begin
during the fall when they aggregate in large numbers in search of an
overwintering site. In their native
lands H. axyridis would normally
overwinter in cracks and crevices of cliff sides and rock outcroppings (Riddick,
et al., 2000). In Ohio where such structures are relatively uncommon, the
preferred overwintering site has become individual homes. This aggregation usually begins in early
October. Large swarms can be found
moving across the landscape and settling on or around individual homes. During
the swarming period homeowners report the inability to leave the house without
being covered with beetles that often times bite. When in the home in large
numbers H. axyridis causes much
aggravation to the homeowner because these beetles often find their way into
food and drink, disrupt activities such as sleeping and reading and when
disturbed will reflex bleed a yellow-orange, foul-smelling liquid that stains
most surfaces. Additionally, H.
axyridis has been shown to induce allergic reactions in some people
(Yarbrough, et al., 1999).
Once the weather turns consistently cold the beetles settle into their
overwintering sites on or just inside the home. If they remain dormant throughout the
winter the beetles are less of a concern to the homeowner. However during warm spells in the winter
and spring the beetles become active and often find their way into the home and
become a nuisance again.
For years very little was done to address the H. axyridis nuisance problem because of
the desire to preserve it as a biological control agent. However the nuisance
problem has grown tremendously and now many homes throughout Ohio are being
invaded each year. In order to assess the extent and nature of the H. axyridis nuisance problem in Ohio a
survey of residents was conducted along with an evaluation of selected
insecticides for their toxicity against the beetle.
In a follow up effort in the fall of 2001 the Ohio Lady Beetle Project (OLBP)
participants were instructed to call the Hotline and report the date that the
lady beetles arrived at their home in large numbers or swarms. Dates of arrival were received from 286
project participants. Daily temperature highs were then obtained from National
Weather Service stations throughout the state. This weather data was used
because H. axyridis flight appears to
be temperature dependent. The
temperature data were then graphed against the arrival data for a given region
in order to discern a pattern of predictive events. Regions were comprised of
the resident county of the weather station and the counties immediately
surrounding. Since all of the regional graphs were very similar a statewide
graph was created using daily high temperature means and a summation of the
arrival data.
The OLBP participants were also asked to record all mitigation activities
they undertook against H. axyridis
during the fall of 2001 and submit that information on data sheets provided by
the project staff. Data sheets have
been received from 41 people. The
information from the data sheet was recorded and a summary of treatment options
was produced. Included in this
information were the treatment method, cost and efficacy. The final portion of the project consisted of testing five pyrethroid
insecticides on their residual effect and efficacy as a killing agent against H. axyridis, since pesticide
application to the exterior of the home appeared as the most promising
mitigation technique at the time. The beetles were collected from soybean fields
located at the Snyder Farm of the Ohio Agricultural Research Development Center
during August and September of 2001. Twenty-five petri dish size white vinyl
siding disks were treated with insecticides on 27 Aug 2001. Insecticides tested
were: Demand CS (9.7% lambda-cyhalothrin, rate of 0.634 ml/100 ml water); Talstar (7.9%
bifenthrin, rate of 0.781 ml/100 ml); Tempo SC (11.8% cyfluthrin, 0.423 ml/ 100
ml); Suspend SC (4.75% deltamethrin, 1.16 ml/100 ml); and Demon EC (25%
cypermethrin, 1 oz/gal or 0.78 ml/100 ml). Each treatment was replicated 5
times. The disks were then placed outside during the day and exposed to natural
sunlight for 21 days. Disks were only brought in at night, to conduct bioassays,
and to avoid dew or rain events. Each disk was exposed to approximately 130 hour
of daylight. On September 18, five beetles were placed on each insecticide
treated disk plus and untreated control for one hour. After exposure the beetles
were then removed and placed on filter paper in petri dishes and provided with
water. Beetles were evaluated at 6 times period (16 hours, 24, 40, 48, 64 and 78
hours after treatment) and placed in 3 categories, alive, dead, or moribund.
Data were analyzed using the analysis of variance function and means were
separated using Fisher’s Protected LSD. (SuperAnova, Abacus Concepts, 1991).
The survey respondents were then asked to describe their home. Over half (57%) of the respondents had two-story
homes while 31% had a single story.
On the exterior of the home, 54% had wood, 43% had vinyl and 23%
brick. However the results did not
indicate that either house or roof color was a determinant for an infestation
problem. It has been reported elsewhere that H. axyridis has a preference for light
colors. (Nalepa et al, 1999) As Figure 2 shows, even when the data
was broken down into the low, medium and high population categories the beetles
equally invaded houses of light, medium or dark color. The average house age of the survey respondents was 53 years. The data did
not indicate that house age was a determinant of an infestation problem. However older houses were slightly more
likely to experience high populations of lady beetles. The survey respondents were also asked to describe the landscape immediate
surrounding their home in the four directions (N, S, E & W). Figure 3 shows that having trees or
a forest to any of the four cardinal directions was a good indicator of a H. axyridis infestation problem. Questions were also designed to gain an understanding of the nature of the
infestation problem experienced.
The respondents were asked in what room and on what surface did the
beetles most frequently appear. Most of the people experienced problems in their
living rooms (58%), bedrooms (53%) and kitchens (46%) with the beetles appearing
most frequently on the windows (86%) and ceilings (64%). When asked about the
problems associated with a H.
axyridis infestation, the survey respondents most frequently mentioned that
the beetles produced a foul odor (77%) and stained various surfaces (71%)
throughout the house. However a
notable number also indicated that they were bitten by the beetles (42%) or that
the beetles ended up falling into their food and drinks (41%). The respondents were also asked if they experienced an allergic reaction to
the beetles. Overall 13% of the
respondents reported having allergic reactions and 6% actually had that reaction
confirmed by a doctor. Furthermore, the data does suggest a dose response when
broken down into the high, medium and low population categories (Figure 4). More of the respondents
who reported allergic reactions also reported having high populations of beetles
in their homes. Finally, the respondents were asked what action they took against the lady
beetles. The large majority of the
respondents used vacuuming (90%) as their primary method of managing their H. axyridis infestation problem. Other methods used included applying
pesticides (44%), sealing and caulking (34%) and trapping (7%). Six percent of the survey participants
also reported that they took no action against the beetles. When asked how pleased they were with
the results of the actions they took, only 1% of the group reported being
satisfied. The response from the OLBP participants regarding the date of arrival of the
H. axyridis swarms at their location
provided enough information to track the migration of the beetles to
overwintering sites. There were three periods of migration, October 2-3, October
9-11 and October 20 with the middle period being the most notable. When this data was graphed against high
temperature means for the state a predictive pattern of temperature declines was
revealed. Figure 5 shows that during the days
before each flight period the temperature dropped quickly. The low temperature for those days
(September 30 – October 1, October 7-9 and October 18 – 19) fell to near or
below freezing. Then on the next
day over 18°C
the beetles began their migration. While only a small number of OLBP participants have returned the data sheets
detailing actions taken against the lady beetle, some of the information
indicates a direction for research on better management techniques. The most
popular and reportedly effective method of reducing the number of H. axyridis in the home was to apply a
pesticide on the exterior of the house.
The products used by homeowners most frequently contained the pesticides
cyfluthrin, permethrin and tralomethrin.
Cyfluthrin also topped the list of chemicals applied by a pest control
company followed by lambda-cyhalothrin and the combination of deltamethrin plus
cypermethrin. 58% of the respondents reported applying the pesticides after the
first swarm of H. axyridis
arrived. The other respondents
applied their pesticides anywhere from one week before and up to the day of
arrival. The respondents were also
to rate the efficacy of the treatment. All of the treatments that were applied
by a professional were rated as significantly reducing the number of beetles
that got into the home. The
homeowner-applied pesticides were rated slightly less effective. Cyfluthrin, Deltamethrin + Cypermethrin,
lambda-Cyhalothrin and Permethrin were consistently rated as effective
chemicals. Furthermore the timing of the application of the chemical does not
appear to affect its efficacy. Pesticides applied shortly after the lady beetles
arrived received nearly as high ratings for efficacy as those that were applied
before the beetles appeared. Homeowners also reported using other methods to exclude H. axyridis from their home. Caulking to seal gaps and holes and
screening any large openings such as vents were other popular mitigation
techniques. Most reported caulking
around windows and doors in addition to filling in any other visible
cracks. This method alone was not
viewed as successful in keeping the beetles out of the home. However when used in conjunction with
other methods, especially exterior pesticide sprays, the survey respondents
indicated a significant reduction in the number of beetles entering the home.
Camphor cakes or oil, vanilla candles and bay leaves were other exclusion
methods used by some homeowners.
The camphor cakes or oil and bay leaves were placed around the windows,
usually between the screen and the window on the exterior side. The candles were used with the intent of
keeping H. axyridis out of the room
in which they were burned. Most of
the research participant indicated that the botanicals had no observable effect
on their H. axyridis population. However, a few people with only a
moderate infestation problem reported that camphor worked well for them. Most of the data sheets also indicated that people relied heavily on
vacuuming, usually numerous times per day, to manage their H. axyridis population. Some people even indicated that they
purchased a vacuum or shop vac just for this purpose. This method did not eliminate H. axyridis from the home but did
provide some help. It should be
noted that all beetles vacuumed were disposed of, not released outside. Very few people tried trapping devices to help manage their H. axyridis problem. The few that used sticky traps (both
white and yellow) found them to be ineffective. Black light traps were also
suggested. A few people constructed
homemade versions and also found them to be useless. The final method employed by some homeowners was to apply a pesticide on the
interior of the home, usually around the windows and doors. Most of these chemicals were applied by
the homeowner who commonly used permethrin. The professionally applied chemicals
included chlorpyrifos and chlorpyrifos with permethrin. All of the homeowners
who applied pesticides to the interior of their home also applied them to the
exterior. And all of these people
found this combination of treatments to be successful. The results from the long-term efficacy test of the five pyrethroid
pesticides showed some clear differences. Table 1 shows the percent of
beetles that are dead or moribund in each treatment after 78 hours. All
treatments provided some level of control. The lambda-cyhalothrin and
deltamethrin treatments were the best with over 95% of the beetles either dead
or dying. The bifenthrin treatment was next with 84% and statistically the same
as the deltamethrin treatment. Cyfluthrin and cypermethrin killed only about 50%
of the beetles at this time. The number of dead or moribund individual at the various times is presented
in Figure 6. At the 16-hour
reading, over 80% of the beetles were dead or dying in all the treatments.
However over time some beetles recovered and were alive 40 to 48 hours after
exposure, particularly in the Demon and Tempo treatments. After 48 hours, those
beetles that were classified as dead or dying remained in that condition. Graphing the reported arrival dates of the beetles against the temperature
highs shows a predictive weather pattern for the initiation of migration. While needing further research, it
appears that H. axyridis are prompted
to search for overwintering sites on the first day over 18°C
after a significant drop in temperature, usually to near freezing. The most
effective mitigation treatment reported was the application of pesticides to the
exterior of the home. Combining
this treatment with others such as vacuuming, caulking or screening only
increased their success. While the importance of pesticides as a tool to combat
a H. axyridis infestation was
evidenced by the treatment reports, the efficacy test on these chemicals shows
the choice of pesticide is important. Our results suggest that one application
to the exterior of a vinyl sided house with lambda-cyhalothrin, deltamethrin or
bifenthrin should give at least 3 weeks of protection and may provide seasonal
control of H. axyridis.
The work of the Ohio Lady Beetle Program indicates the need for much more
research. The issues surrounding H. axyridis are complicated at
best. Research needs to commence to
help find options for homeowners to keep H. axyridis from infesting their homes
while at the same time preserving the beetle for its valuable biocontrol
function. LaMana, M.L. and Miller, J.C. 1996. Field Observations on Harmonia axyridis Pallas (Coleoptera:
Coccinellidae) in Oregon. Biological Control. 6:232-237. Nalepa, C.A., Kidd, K.A. and Hopkins, D.I. 2000. The Multicolored Asian Lady
Beetle (Coleoptera: Coccinellidae): Orientation to Aggregation Sites. J.
Entomol. Sci. 35(2):150-157. Riddick, E.W., Aldrich, J.R., DeMilo, A. and Davis, J.C. 2000. Potential for
Modifying the Behavior of the Multicolored Asian Lady Beetle (Coleoptera:
Coccinellidae) with Plant-Derived Natural Products. Annals of the Entomological
Society of America. 93(6):1314-1321 Tedders, W.L. and Schaefer, P.W. 1994. Release and Establishment of Harmonia axyridis (Coleoptera:
Coccinellidae) in the Southeastern United States. Entomological News. 105(4):
228-243. Yarbrough, MD, J.A., Armstrong, MD, J.L., Blumberg, MD, M.Z., Phillips, BS,
A.E., McGahee, RN, E., and Dolen, MD, W.K. 1999. Allergic rhinoconjunctivitis
caused by Harmonia axyridis (Asian
lady beetle, Japanese lady beetle or lady bug). J Allergy Clin Immunol.
104:704-705.INTRODUCTION
The multicolored Asian lady beetle, Harmonia axyridis, was introduced many
times into North America to serve as a biological control agent, first in 1916
(California) and as recent as 1985 (Connecticut) (Tedders and Schaefer, 1994).
The first established populations of H.
axyridis were reported in Mississippi and Louisiana in 1988 (Chapin and
Brou, 1991). Since that time H. axyridis has become a
well-established predatory insect in many parts of the United States, including
Ohio (Horn, 1996). By outcompeting native populations, H. axyridis has become the dominant
species of lady beetles in Ohio, successfully managing populations of aphids,
scale insects and other soft-bodied insect pests on many types of plants and
trees. However, the perceived successful release of non-native generalist
predators such as H. axyridis for
biological control has not been without controversy. In such introductions there have usually
been long delays between release and establishment, displacement of other guild
members and negative non-target impacts. (LaMana and Miller, 1996). And it is
these non-target impacts that are the concern of homeowners across the state and
region. While much heralded for their activity as a bio-control agent during the
growing season, H. axyridis becomes a
serious nuisance pest to homeowners during the fall, winter and early spring.
MATERIALS AND METHODS
In May of 2001 a statewide survey of homeowners
experiencing a H. axyridis nuisance
problem was conducted. A toll-free number (The Ohio Lady Beetle Hotline) was set
up so that individuals who had experienced a H. axyridis nuisance problem could call
and request that a survey be sent to them. County Extension Agents advertised
the existence of the Hotline throughout the state. The survey was designed to
gain a basic understanding of the kinds of houses that are infested by H. axyridis and the specific nature of
the infestation experienced. All of the responses to the survey questions were
entered into an Excel spreadsheet and summary statistics produced. In some cases
to further refine the results, the data were grouped into three categories,
whether the respondents reported having low (100’s or less), medium (thousands)
or high (millions to “too many to count”) populations of beetles.
RESULTS
By the time that the survey results had begun to be tabulated in
late August nearly 1550 surveys had been sent and of those 1148 returned. The
survey respondents were initially asked when the beetles first became a problem
in and around their home. A few
respondents reported that their problem began in the late 1980’s, but the
majority of respondents reported dates in the 1990’s. The map (Figure 1) shows how the problem
has spread from a few counties in eastern and southeastern Ohio in the early
1990’s to nearly half of the counties in Ohio. Although the map does not show
the complete distribution of the H.
axyridis nuisance problem since the survey was not promoted equally in all
counties, it is representative of the relative movement of H. axyridis throughout Ohio.
DISCUSSION
The multicolored Asian lady beetle has become a significant
problem for many Ohio residents.
The results of our survey indicate that the H. axyridis infestation problem, while
originating in eastern and southern Ohio, has spread throughout many parts of
the state in the past decade. The average type of house experiencing a H. axyridis infestation problem is 73
years old, two-story, wood or vinyl sided and has lots of trees on at least
three sides of the house. The colors of the house and roof are not a determining
factor for an infestation problem. When H. axyridis invade a home they are found
in rooms throughout the house but most frequently in the living room and
bedrooms and usually on the windows and ceiling. The most irritating problems
associated with a H. axyridis
infestation are the foul odors the beetles emit and the stains resulting from
their hemolymph when they reflex bleed. However, biting and food contamination
are also significant concerns. An associated health problem is emerging as
evidenced by the 13% of the respondents reporting dermal or respiratory allergic
reaction to the beetles. Vacuuming is the primary management option utilized by
the survey respondents to deal with the beetles. Others have also tried pesticides but
nearly everyone has been dissatisfied with the results of the methods they have
used.
REFERENCES
Horn, D.J. 1996. Impacts of Non-Indigenous Arthropods on
Biological Control. Midwest Biological Control News.
http:www.entomology.wisc.edu/mbcn/fea312.html