predator and prey among chard blossoms

It lurks among the flowers of the Swiss chard. This assassin bug waits quietly, alert and ready to pounce. It sees me, which makes it hard to photograph because it keeps moving around to the far side of the stalk. Like most predators, it has an intelligent, deliberate way of behaving.

This one is in the family Reduviidae (reh-doo-VEE-ih-day, Wikipedia), possibly related to the European species Coranus griseus (photo at Flikr by Joao Coelho), but most likely not the same species. Note the characteristic “hunchback” appearance and the spotted edge of the abdomen.

Assassin bugs are related to the non-predatory shield bugs (here’s a previous post about a shield bug).

Some can administer a painful, venomous bite with their piercing mouthparts. They violently attack their prey, which can be much larger than themselves, and subdue it with a poison bite. Then they suck out the prey’s inner fluids, leaving behind an empty shell.

These are vicious little hunters. Some assassin bugs even specialize on mammalian blood, including the notorious kissing bug of Mexico and the southwestern US, also in the Reduviidae (basic kissing bug facts from University of Arizona).

Several days after the first pictures were taken, this pair were discovered in a state of mutual … well, they were having a good time, no doubt. They were on this chard flower stalk all morning and all afternoon, and they were still together at dusk.

The next morning they had gone away.

Looking at insects like these, one might wonder at their form. From an evolutionary perspective, what is the advantage of the sharp-edged shoulder humps? Why are there prominent spots along the edges of the abdomen? Are these sexually selected traits like guppy colors or deer antlers? Do they serve some other function?

Assassin bugs like to hang out in flowers, waiting for… well, this little critter, for example, a flower fly in the Syrphidae who is happily eating pollen among the same chard flowers. I think this lucky one got away.

Look to this previous post for another flower fly.

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