Dark Banquet - Bill Schutt [68]
In addition to bed bugs, the Heteroptera contain a parade of insects with nasty-sounding names like stink bugs, squash bugs, and water scorpions. Assassin bugs (Reduviidae) are another notorious family of hemipterans. Unlike their bed bug cousins, though, some assassin bugs can transmit serious ailments to the humans they feed upon. In fact, these insect vampires (also known as cone-nosed bugs or kissing bugs) deposit feces containing the parasitic flagellate Trypanosoma cruzi onto their victim’s skin. Itching the bug bite rubs the infected excrement into the wound, allowing the parasite to enter the bloodstream. From there it can invade organs like muscles. In severe cases, the ailment is known as Chagas’ disease, in which the parasites can cause serious damage to nerves of the gastrointestinal tract and the electrical conduction system of the heart. Charles Darwin was, in fact, bitten by assassin bugs in South America, and it’s been suggested that Chagas’ disease may have been responsible for the lifelong health problems he experienced upon his return to England.
Although bug can refer to diseases like influenza, as well as just about any insect or small arthropod (e.g., spiders and ticks), only heteropterans are considered “true bugs” by entomologists. This is because they all share some rather specific anatomical characteristics. For example, many insects have two pairs of wings (forewings and hind wings). In most heteropterans, the forewings are hard at the base and membranous toward the tip (hence their name, from the Greek for “different wings”). One take-home message is that “all bugs are insects but not all insects are bugs.”
Strangely enough, although bed bugs share anatomical, developmental, and behavioral similarities with other heteropterans, they don’t have functional wings. The posterior wings of cimicids are absent and the anterior pair is vestigial. Vestigial organs are nonfunctional remnants of structures that were functional in the ancestors of that organism. For example, blind cavefishes (belonging to the families Amblyopsidae and Characidae) have tiny, functionless eyes. By all indications, these sightless swimmers evolved from ancestral species that could see. Presumably, some of these fish migrated into new environments (caves), where they eventually lost their visual senses in much the same manner as other troglodytes like blind salamanders and some cave crickets. The sightless eyes that remain result from portions of the fishes’ genetic blueprint (its DNA) that have remained unchanged from the ancestral versions. As a result, these old sections of DNA are still cranking out remnants of the old anatomical features—even though they don’t function anymore.*105 In bed bugs, one pair of stubby functionless wings (hemielytra) is all that remains of what were probably two working pairs of wings in bed bug ancestors. Presumably, the loss of wings occurred as these ancient bugs evolved a lifestyle in which birds and bats spread them from place to place, thus rendering their own wings unnecessary.
Speaking of bugs, the English word bug apparently derives from the Welsh bwg. In its original form, bug (or bugg) referred to a ghost or hobgoblin, which is how it appeared in the Coverdale Bible (1535) and in several works by William Shakespeare (including Hamlet).†106 In the 1622 play The Virgin Martyr, bug appears to have been used for the first time to describe an insect infestation (“We have bugs, Sir!”). Until then, wall lice and Cimices had been used to describe Cimex lectularius.
Of course, since the seventeenth century, the word bug has developed a number of additional meanings. The phrases “putting a bug in someone’s ear” or “having a bug up one’s butt” may very well have originated with the medicinal use of leeches (but I’m only speculating here). Used as a verb, bug can describe certain unwelcome attentions or the covert placement of surveillance equipment. It