Amateur Naturalist: Why Hair And Bristles On Bugs?

Picture 1: A Clouded Sulphur butterfly sips nectar while a nearby honeybee collects pollen. Courtesy photo

 
By ROBERT DRYJA
Los Alamos

Many species of plants produce flowers in spring and the resulting seeds then develop over the summer.

In contrast, the Chamisa bush, also called rabbit bush, becomes covered with bright yellow flowers in the autumn.

It therefore becomes a source of nectar for insects. A single bush may have a variety of insect species busily going from flower to flower at the same time. The insects may be so focused on finding nectar that they stay on the flowers rather than flying away when a person approaches them. It therefore is relatively easy to look for similarities and differences among the species. The hairs/bristles of four kinds of insects and their coloration now will be considered.

Picture 1 shows a honeybee and a clouded sulphur butterfly close to one another. Both are sipping nectar as they fly from flower to flower. The honeybee is gathering pollen grains as well. 

Picture 2: A Clouded Sulphur butterfly has unwound its proboscis to sip nectar while standing on its long slender legs. There are only some hairs at the base of its legs and its thorax. Courtesy photo

Picture 3: A honeybee is carrying a load of pollen on its back legs after combing the pollen from the rest of its body. The honeybee in contrast to the Clouded Sulphur butterfly has hairs over its entire body including its eyes. Pollen grains have become attached to the hairs everywhere. The honeybee has groomed pollen into ‘baskets’ on its back legs. It not only is eating nectar immediately at the bush, it will be taking food back to its hive for other bees. Courtesy photo

A species of tachinid fly called Adejeania looks somewhat like a honeybee but has a squat body in comparison. It also has red coloration and distinctive black bristles. The tachinid fly sips nectar like a honeybee from the flowers on the chamisa bush, but pollen grains are not apparent on its bristles. The purpose of the bristles on a tachinid fly are not obvious. Perhaps they help repel predators. An inexperienced predator may eat one tachinid fly and then have the needle-like bristles stabbing inside its mouth. It then will not attack other tachinid flies when it sees their bristles. This is analogous to the colors of monarch butterflies that warn predators that they are poisonous.

Picture 4: An adejeania Tachinid fly with its black, distinctive bristles sipping nectar. Courtesy photo

The Masked Hunter has a remarkable adaptation for the hairs on its body. The hairs are sticky and so can hold dust and dirt. It may look more like a small bit of wood or part of a leaf when its legs are folded close to its body. This camouflage occurs during the nymph stage of growth. The adult looks more like a usual insect. The Masked Hunter is a member of the assassin bug family. It can inflict a deadly stab into other insects when it is hunting them for food. It also can protect itself by inflicting a painful sting if it is being hunted in turn.

Picture 5: Bits of dirt cover the flat body and legs of the nymph of a Masked Hunter. Courtesy photo

Picture 6: The adult Masked Hunter has just killed another insect. Courtesy photo

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