Assassin Bug Ambushes Its Prey

assassin bug

This juvenile milkweed assassin bug has perfected its hunting skills. It’s continued successes will be reflected by its growth to maturity.

By Les Harrison
Wakulla County Extension Director

There are few experiences which compare to the thrill of a successful hunt. The pursuit of the quarry may have physical, as well as intellectual, challenges which require discipline to overcome.

There are the unanticipated obstacles which add to the interest and uncertainty of the episode. A chance, be it ever so slight, of failure will improve the hunter’s focus and attention to the ultimate target.

Achieving the ultimate goal of taking the prize can have more psychological satisfaction than the value of the prize itself. Still the prize itself has value, and for the hunters which are insects the prize is another meal.

Among the many native hunter insects is the milkweed assassin bug, Zelus longipes. Sometimes known as the long-legged assassin bug, it displays the bright coloration of a novice deer hunter especially when in juvenile stages of development.

This species is common in southern North America, especially in the Gulf Coast and South Atlantic states.

Additionally, variations on this species are found in Central America, the West Indies and much of South America.

This winged bug is slightly less than 3/4-inch long and has a slender, straight beak with piercing-sucking mouthparts. Their piercing and sucking mouthparts have three-segments.

When their beak is not in use it is bent back and held under the thorax in a groove. It is carried much like a folding pocket knife, but extended when needed.

Adults and nymphs have a pear-shaped head, constricted neck and long hairy legs giving this insect an awkward, lanky appearance. Unlike many of the insects in Wakulla County, the shape and appearance is generally the same throughout its life.

Unlike some of its domestic cousins which are rarely seen during the day and are hiding in leaf litter near their intended host, milkweed assassin bugs spend the days pursuing their prey.

With their bright orange coloration, their presence is easily observed when contrasted with the green leaves.

The strategy used to catch its prey is known as the “sticky trap strategy.” Like many ambush bugs, the milkweed assassin bug attacks prey after hiding inside foliage with its forelegs raised in the air.

The exposed forelegs are covered with a viscous material which acts as a glue resulting in the prey’s entanglement. The target insect is rapidly paralyzed when the milkweed assassin bug inserts its beak into the host body.

Enzymes are released into its prey to dissolve its tissue, and the dissolved liquid is vacuumed out. This tiny predator can feed on prey that may be up to six times their own size.

Problems can arise when these insects encounter humans. It is capable of delivering a nasty surprise to the unsuspecting gardener working in plants who disturbs this ambush predator.

Not usually a life threatening injury, it is painful. The bite is purely a defensive reaction to a perceived threat.

The good news is this assassin bug has little inclination to enter homes. The green leaves and pretty flowers are an ideal habitat for the milkweed assassin bug’s hunting activities.

Milkweed assassin bugs may not be thrilled by successful hunts, but they are well fed.

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