What You Should Know About the Milkweed Assassin Bug
There are several species of insects called assassin bugs which range in length from ½ inch to 1½ inches long. Most are brown or black with bright colored markings with a small head and prominent beak. One of the most common assassin bugs encountered in Florida is the milkweed assassin bug, also known as the long-legged assassin bug.
This species exhibits enormous variation in size and color, but populations in the southern U.S. are distinctively orange and black in color. Adults and nymphs have a pear-shaped head, constricted neck, and long hairy legs. Their piercing and sucking mouthparts consist of a three-segmented beak, which at rest is held in a groove under the thorax.
Reproduction And Distribution
The milkweed assassin bug is widely distributed in southern North America, Central America, South America, and the West Indies. The eggs are brown in color with a light brown, cap-like structure that features a central pore. Eggs are cylindrical and elongated in shape and are laid in clusters of 15 or more, cemented at the base, and covered with viscous material from the insect.
Close up of milkweed assassin bug. Photo courtesy of University of Florida
There are five instars that resemble adults but lack wings. Early instars are mainly orange and take on adult coloration as they develop. Adults are known to over-winter.
Beneficial Activity
The milkweed assassin bug attacks prey after hiding inside foliage with its forelegs raised in the air. The forelegs are covered with a viscous material which acts as a glue, trapping the prey. The insect then paralyzes its prey by inserting its stylet into the insect and prepares to feed by releasing enzymes into its prey to dissolve the host’s tissue, and later sucks up the dissolved liquid using its stylet as a straw.
Z. longipes can feed on prey that may be up to six times their own size. But with increasing prey size the handling and feeding time also increases, allowing the insect to become vulnerable to other predators such as birds and other insects.
Although they are not a threat to humans, assassin bugs can bite if not handled properly, causing a burning sensation with swelling that may last for several days.
Judicious use of insecticides and leaving unsprayed refugia can help conserve these and other beneficial insects.
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