|
Stinging or Venomous Insects and Related Pests
P. G. Koehler and F. M. Oi
Millions of people in the United States are injured from venoms produced
by insects and other arthropods each year. Of these injuries about 25,000
result in severe injuries and about 32 result in deaths.
Venoms
Venomous insects and other arthropods produce venoms that can be
classified as:
1. Venoms that produce blisters (vesicating toxins) (e.g., blister
beetles, certain stinging caterpillars, millipedes).
2. Venoms that attack the central nervous system (neurotoxins) (e.g.,
black and brown widow spiders, bark scorpions, certain ticks, Hymenoptera,
wheel bugs).
3. Venoms that destroy tissue (cytolytic and haemolytic) (e.g.,
Hymenoptera, fire ants, ground scorpions, mites, chiggers, wheel bugs, brown
recluse spider).
4. Toxins that prevent blood from clotting (haemorrhagic) (e.g., lice,
fleas, ticks, mites, true bugs, biting flies).
Allergic Reactions
Humans differ greatly in their reaction to arthropod venoms. Allergic
reactions are often more important than the toxic effects of arthropod venoms.
Of individuals who die from arthropod venoms, 96% had an allergic reaction.
Allergic reactions to stings or bites are when something happens to a part of
the body other than the immediately affected area. Allergic reactions are
classified according to the severity:
1. Slight general reaction-inflammation, welts, itching, malaise and
anxiety.
2. General reaction-a slight general reaction, plus 2 or more of the
following symptoms: swelling, wheezing, abdominal pain, nausea or vomiting.
3. Severe general reaction-any of the above, plus 2 or more of the
following: difficulty in breathing, difficulty in swallowing, hoarseness,
confusion or feeling of impending disaster.
4. Shock reaction-any of the above, plus 2 or more of the following:
cyanosis, fall in blood pressure, collapse, unconsciousness or incontinence.
Insect stings result in rapid progression of toxic effects. Of 208 deaths,
80% occurred less than one hour after being stung by Hymenoptera (bees, wasps,
yellow jackets, or hornets). Spider bites, however, have a longer time
interval between bites and death, with 89% of 54 victims dying more than 12
hours after being bitten. Statistics also reveal that of snakebite victim
deaths, 17% died 1 to 12 hours after being bitten and 64% between 12 hours and
2 days.
What to Do
Insect stings require quick, prompt action.
1. The causative organism must be captured, saved and identified.
2. If a general allergic reaction is suspected, or the victim has a
history of hayfever, allergy or asthma, a doctor should be contacted
immediately.
3. Venom that is haemolytic, haemorrhagic or vessicating can cause
marked swelling or discoloration at the sting or bite site. Keep victim warm
and quiet until a physician is reached.
4. Venom that is neurotoxic can cause little or no swelling or
discoloration at the sting or bite site. Apply ice to the site or immerse the
affected part of body in ice water until a physician is reached.
5. Persons who have exhibited a severe allergic reaction in the past to
arthropod venoms or have a history of asthma, hayfever or allergies should:
* Undergo skin testing to determine hypersensitivity to
arthropod venoms.
* Carry identification or tags noting hypersensitivity.
* Consider desensitization (immunization).
* Carry an insect sting kit (available only with a physician's
prescription).
Prevention of Stings
Several procedures can be used to minimize the danger of being stung by
venomous arthropods.
1. Avoid mowing lawns or working with flowering ornamentals when bees
and wasps are collecting nectar.
2. Don't walk barefooted in the yard.
3. Sweet items like soft drinks, ripened fruits and watermelons attract
bees and wasps. Keep these items covered outdoors. Pick fruit as it ripens and
dispose of rotten fruits.
Some Common Venomous Arthropods
Bees
Bees are often confused with wasps. Although closely related, they differ
in many ways. Bees feed pollen and nectar to their young. They are beneficial
insects that pollinate fruits, vegetables and many other plants. The most
common bees are the honey bee (Figure 1 ), bumble bee ( Figure 2 ), and
carpenter bee ( Figure 3 ). Bees are not commonly serious problems and usually
require no control.
 |
CREDITS: James Castner, University of Florida
Figure 1. Honey bee.
CREDITS: James Castner, University of Florida
Figure 2. Bumble bee
 .
CREDITS: James Castner, University of Florida
Figure 3. Carpenter bee.
When stung by a honey bee, scrape the bee's stinger out of the wound
immediately. Be careful not to pull it out. If you do, you will force poison
into the wound. If the stinger is not removed, the poison gland attached to
the stinger will continue to pump poison into the wound for several minutes.
Wasps and other bees do not leave a stinger and are capable of stinging many
times. At certain times of the year (spring and early summer), honey bee
colonies divide by swarming. Swarms are not usually a problem unless they land
in an inconvenient spot or enter a building. A honey bee colony in a building
must be removed after it has been killed to prevent problems from odors of
decaying bees, honey and other pests.
CREDITS: James Castner, University of Florida
Figure 4. Honey bee swarm in tree.
Wasps, Hornets, yellow jackets ( Figure 5 ), Polistes (Figure 6 ), mud daubers (
Figure 7 ) and the cicada killers ( Figure 8 ) are all wasps.
CREDITS: James Castner, University of Florida
Figure 5. Yellow jacket.
CREDITS: James Castner, University of Florida
 .
Figure 6. Polistes, paper wasp
CREDITS: James Castner, University of Florida
 .
Figure 7. Mud dauber wasp
CREDITS: James Castner, University of Florida
Figure 8. Cicada killer.
They are generally considered to be beneficial because they attack and
destroy many harmful insects found around homes and gardens. Hornets and
yellow jackets kill such pests as house flies, blow flies and various
caterpillars. Polistes are predators of corn earworms, armyworms and many
other garden pests. Though beneficial, wasps also attack people. If disturbed,
hornets, yellow jackets and Polistes will sting. Mud daubers and cicada
killers usually are not as aggressive and will not sting unless touched or
accidentally caught in clothing. If wasps build nests on houses or in bushes
where children play or living activities are carried on, nest destruction or
chemical control is necessary. Wasps can usually be identified by their nests
and their location. Hornets, Polistes and mud daubers build nests above the
ground. Hornets and Polistes nest in trees, shrubbery and under eaves. Mud
daubers nest under eaves, porch roofs or similar sheltered areas. Yellow
jackets usually build their nests in the ground, but sometimes build them
above the ground. Cicada killers nest in the ground.
Hornets and yellow jackets build football-shaped paper-like nests
( Figure 9 ). Polistes build paper-like nests that resemble a honeycomb (Figure 10).
Mud daubers build clay or mud-cell nests. Cicada killers dig homes about one
half inch across and pile the excavated soil around the opening.
CREDITS: James Castner, University of FloridaFigure 9. Hornet nest.
CREDITS: James Castner, University of Florida
Figure 10. Polistes wasp nest.
Hornets, yellow jackets and Polistes are social insects and their colonies
develop in a similar way. Adult females make up two castes: queen or fertile
females which lay eggs; workers or sterile females which feed larvae and may
lay eggs without mating if the queen dies during the season. In the fall,
queens and males leave the nest and mate. The male dies and the surviving
queens hibernate in cracks of rocks, under bark of trees, in buildings, or in
the ground. In the spring the queen comes out of hibernation and builds a nest
with a few shallow cells. An egg is laid in each cell and these hatch into
worker larvae in 2 to 3 days. The queen feeds these larvae which develop in 12
to 18 days and spin cocoon caps over the cells and change into pupae. After
the first brood emerges the queen resumes egg laying. The workers take charge
of the nest, enlarging it and caring for the new larvae.
Mud daubers are solitary wasps. Each female constructs a clump of mud
cells. There is no worker caste. In the spring, young adults come out of their
nests and mate. The female then build mud-cell nests. After she completes the
nest she captures about 20 spiders, paralyzing each with her sting as she
catches it. Spiders are stored in the cell and she lays an egg on one of the
spiders and caps the cell with clay. This is repeated until she has built one
nest containing 6 to 20 cells. She may then build other nests in other
locations. Once a nest is finished, she leaves it and never returns. The
larvae hatch from the eggs and feed on the paralyzed spiders. Complete
development takes place in the cell. One to three generations can develop in a
year.
The cicada killer is also a solitary wasp. Its habits are similar to the
mud dauber except it constructs its cells in the soil and provisions the cells
with cicadas.
When a wasp stings it injects a venomous fluid under the skin. The venom
causes a painful swelling that may last several days. In some cases a wasp
sting may cause severe illness or even death.
Control
Wasps can be easily controlled by applying insecticides to the nest.
However, there is usually a certain amount of risk. Nests should be treated at
night to minimize the danger of being stung or protective clothing should be
worn. Whatever spray is used, it should have a quick knockdown.
Copyright Information
This document is copyrighted by the University of Florida, Institute of
Food and Agricultural Sciences (UF/IFAS) for the people of the State of
Florida. UF/IFAS retains all rights under all conventions, but permits free
reproduction by all agents and offices of the Cooperative Extension Service
and the people of the State of Florida. Permission is granted to others to use
these materials in part or in full for educational purposes, provided that
full credit is given to the UF/IFAS, citing the publication, its source, and
date of publication.
|
