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Milkweed Assassin Bug

Milkweed Assassin Bug Bite

A Milkweed Assassin Bug bite is not dangerous to humans, but it can be highly unpleasant. This is because the Milkweed Assassin Bug or Zelus longipes, injects a salivary secretion via the rostrum and into the skin. This results in an intense burning feeling and an itchy bump at the site of the bite or sting.

Most people report that the pain and burning from such a bite is instant and extreme. Fortunately, this insect is not naturally aggressive and rarely interacts with humans on its own. Most bites occur in gardeners due to accidental contact with this slow-moving species.

The reader should note that a somewhat similar breed of insects called Kissing Bugs, do bite humans regularly and can spread Chagas Disease with serious consequences.

These more dangerous bugs inhabit relatively the same areas as the Milkweed Assassin Bug and are in the same insect family, though there is some difference in appearance.

Where Are Milkweed Assassin Bugs found?

Zelus longipes is mostly found in South America, central Argentina, the West Indies, and throughout southern North America. The states that report the most incidence of this insect include California, southwestern Arizona, the Gulf Coast states and the South Atlantic States. This is most likely due to the insect’s preference for a warm climate and the prey bugs that live there.

Milkweed Assassin Bugs can be found in the following U.S. States according to US Department of Agriculture:

  • California
  • Arizona
  • Texas
  • Louisiana
  • Mississippi
  • Alabama
  • Georgia
  • Florida
  • South Carolina
  • North Carolina

Life Cycle and Lifespan

Assassin Bug

Though this species displays a wide variety of physical characteristics in other parts of the world, the Milkweed Assassin Bugs that live in the US can be distinguished by their tell-tale black and orange coloring. In both the nymph and adult stages of their lives, these insects exhibit a pear-shaped head on a constricted neck and also feature long, hairy legs.

Their sucking rostrum is in three parts and tends to be hidden when not in use, utilizing a groove under the thorax.

These insects only experience one life-cycle in a year, meaning the fully grown insects from the previous year live throughout the winter and start the cycle again in the spring.

Milkweed Assassin Bugs go through 5 distinct forms during their life:

  • Egg
  • 5 Instar Stages of Nymph
  • Adult

After two fully developed insects have mated, the female will lay her eggs in a cluster of 15 or more at a time. This is called a clutch. This is generally done on the underside of leaves where the cluster will be protected from the elements.

  • Egg
    The ovum are light brown and lack ornamentation with an elongated, cylindrical shape. They possess an operculum, or cap-like top that contains a funnel shaped opening and central pore. The shell has a smooth surface and a veil that serves the function of regulating humidity to keep the environment the embryo develops in at a constant. When it comes time for the hatching and releasing the first instars, the operculum opens like a hatch from which the instars emerge into the world.
    First instar
    Lacking wings, the first instars that hatch from the clutch have a somewhat similar appearance to their fully developed versions, though they are much smaller and exhibit some differences. The eyes and antennae are formed at hatching. The abdomen ranges from orange in color to light brown. The legs are mainly dark brown. The main difference between this stage and the appearance they will have when completely grown is the abdomen. The abdomen is rounded with only slight indication of where it will be segmented in adulthood. A first instar tends to measure at approximately 2.61mm in length.
  • Second instar
    The second instar has grown, now measuring at 4.26mm in length. The head and abdomen are more elongated at the second instar stage. The legs are black with white bands and the body has taken on a brownish shade with a mild orange tint. Dark brown wing pads are formed, but wings are not yet present as they will be upon reaching the final stage of development.
  • Third instar
    This stage is very similar to the one that precedes it, though the head and abdomen have further elongated and the abdomen now features more visible bands where the body will segment. The total length of this instar stage measures at 5.73mm long. Scent gland openings are visible in the third instar stage and the wing pads have further elongated as well. The antennae are longer, though the overall coloring of the nymph is the same as the previous stage.
  • Fourth instar
    In this stage the antennae and legs are much longer and black, both featuring pale bands. Once again, the overall length has increased from 2.61mm during the first instar phase, to 7.14mm in the fourth stage. The little guy is really growing and starting to look more like he will when he is done developing. The wing pads are longer still in this stage and have a black color. The abdomen is closer to segmenting and is yellow with prominent black spots.
  • Fifth instar
    In the fifth and final instar stage, the body is nearly full length, measuring 11.29mm. The antennae are long and the eyes are black. The black wing pads measure 3.54mm in length and the body has a much more segmented appearance. At this stage of development, there are whitish yellow stripes along the lateral edges of the abdomen and the insect is nearly fully grown.
  • Adult
    The fully developed Milkweed Assassin Bug has wings and can fly, though they don’t do so often and are rather clumsy in flight. The males of the species are generally smaller than the females by over 2mm. The abdomen is fully formed and segmented and has become the distinctive black and orange color that these bugs are known for. In females, the final segment of the abdomen has a flattened or plate-like appearance. In males the same segment is rounded and cup-like. Females measure at a total length of 18.4mm, while males of the species generally measure at 16.1mm. There is slightly less difference between males and females of the Gulf coast populations of Milkweed Assassin Bugs. The males are slightly larger at 16.8mm and the females run just a little smaller at 18.2mm in length.

Where the Name “Assassin Bug” comes from

Belonging to the family Reduviidae, Assassin Bugs get their name from the means with which they kill their prey. Using their rostrum, they inject salivary fluids that will digest the prey from the inside.

This liquefied mixture of insides can then be sucked out, allowing them to effectively kill and consume other insects and animals that are many times their size.

All members of this insect family are predators with the exception of only a few who drink blood. These members are the aforementioned Kissing Bugs that are named for their habit of biting humans and other mammals near the mouth to feed on their blood.

Although most members of the Reduviidae family are capable of biting humans, only blood drinking members of the family are vectors of disease amongst mammals.

What does a Milkweed Assassin Bug Bite look like?

The Milkweed Assassin Bug Bite is generally small and bump like in appearance. It can be swollen and generally has a red center where the actual sting or bite took place.

Though these are terribly painful bites, most often the effects do not spread beyond the area of the bite itself. These bites do not differ significantly from the appearance of other common bites and often can only be recognized by seeing the actual insect that bit you.

Treatment for Milkweed Assassin Bug Bites

Unless you suspect you were bitten by a blood sucking member of the Reduviidae family or are experiencing signs of anaphylactic shock, you can probably deal with the results of a Milkweed Assassin Bug bite at home yourself.

Though allergies to these bites are extremely rare, they can still happen. Signs of anaphylactic shock include:

  • Hives
  • Intense Itching
  • Swelling other than in the bite or sting site
  • Abdominal cramping
  • Vomiting
  • Diarrhea or extreme nausea
  • Tightness in chest
  • Difficulty breathing
  • Difficulty with swallowing
  • Swelling of throat or tongue

If you are experiencing any of the above symptoms after a suspected Milkweed Assassin Bug bite or suspect a bite from a blood sucking member of the family, seek medical attention immediately.

Home Remedies for Milkweed Assassin Bug Bite Treatment

Though the bite from a Milkweed Assassin Bug is undoubtedly an unpleasant experience, the extreme burning and pain should pass on its own after awhile.

There are some home remedies that will help with the symptoms of the bite if you are certain it was this insect that bit you. You should start by washing the bite with a mild soap and water, followed with the application of an antiseptic ointment.

Over the counter pain medications like aspirin, acetaminophen or ibuprofen should reduce the pain associated with the bite.

If itching is extreme, you can apply calamine lotion or hydrocortisone creams to reduce swelling and discomfort. An ice pack will often provide some relief as well, if you lack any of the above medications.

Clinical Milkweed Assassin Bug Bite Treatment

If you are showing symptoms of Chagas Disease such as fever, rash, fatigue, swelling of lymph nodes, body aches, eyelid swelling, headache, nausea, loss of appetite or diarrhea, you should contact a physician immediately.

Also, if the swelling of the bite site becomes extreme, doesn’t go away, or looks infected, a visit to a doctor is suggested.

Pest Control or Beneficial Insect?

The Milkweed Assassin Bug is classified by the US Department of Agriculture as a beneficial insect due to its feeding habits.

This insect is known to eat many other insects that are harmful to the plants that we grow on farms and in our own gardens. They are particularly useful in cutting down on the populations of various caterpillars and worms that can be devastating to crops.

Three key staples of their diet that do a tremendous amount of damage in agriculture are the fall armyworm, the genista broom moth, and the Asian citrus psyllid.

Since Milkweed Assassin Bugs are beneficial to our gardens and agriculture in general and do not tend to exist in abundant populations of their own, the primary benefits of keeping these insects around far outweighs the minimal risks.

These are a non-aggressive species that rarely comes in contact with or bites humans. Most cases of Milkweed Assassin Bug bites that occur yearly come from people intentionally handling and agitating the bugs, or gardeners not paying attention and inadvertently causing the insect to bite them.

For these reasons, if you encounter one of these unusual insects in your yard or garden, it is recommended that you let it remain and do its job of ridding your plants of much more harmful pests.

Just be careful around the insect. If you respect its territory and don’t bother it, the Milkweed Assassin Bug will cause you no harm.

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