49 Hemiptera – Heteroptera

Hemiptera

Hemiptera is a large, varied order, with more than 55,000 species. Many species are cryptic, feeding on roots or inside galls, meaning that there are probably many more species still to be described. The order name refers to the forewings in one subgroup being hardened or leathery at the base only (“hemi” = “half”), forming hemelytra. There have been a number of different classification schemes in the past, some of which separate the Homoptera (cicadas, aphids, etc.) into their own order, and others which combine the two groups. In this course, I will be using the combined order, Hemiptera.

All members of this order are paurometabolous, and have haustellate, piercing/sucking mouthparts. We will see three suborders in this lab: Heteroptera (true bugs), Auchenorrhyncha (cicadas and hoppers), and Sternorrhyncha (plant parasitic forms).

Heteroptera

The suborder Heteroptera, the true bugs, are so-named because their forewings are partially sclerotized at the base, forming hemelytra. In addition to this distinctive characteristic, the piercing/sucking mouthparts originate at the front of the head: they may point forwards, down, or be tucked up under the body between the forelegs. Some groups are blood-feeders (e.g. bed bugs, kissing bugs) and, thus, very important medically. Several have extremely painful bites (e.g. wheel bugs, giant water bugs, and backswimmers). Superficially, they resemble beetles, but:

• The forewings overlap on the dorsal surface, usually forming an “X” or “Y” pattern
• They have a large scutellum, a triangular sclerite between the bases of the forewings
• Beetles NEVER have sucking mouthparts

There are many different feeding guilds within this suborder. Some species are exclusively herbivorous, some are predators, and some are ectoparasitic on larger animals. A few are omnivorous, e.g. Campylomma verbasci, the mullein bug. It can be a plant pest in some agricultural settings, but also an important biological control agent for other plant pests. Many also have obvious scent glands, which are often more obvious on nymphs. These produce pheromones or defensive compounds, and often smell bad, even to humans.

There are seven infraorders within this suborder. You do not need to know all their names, but they do underlie the sequence in which I will present the most important families for you to know.