The trichoptera insect order consists of numerous species of moth-like insects called caddisflies that grow to be less than one inch long. Caddisflies get their nickname from their body-shielding case-making habit. The insects have two sets of hairy wings, aquatic larvae, and pupate within silky cocoons. Roughly 12,000 trichopterous insect species have been identified thus far, however, about 50,000 exist in and around waters throughout the world.
According to FossilMuseum, the insect orders trichoptera and lepidoptera are related, with the first being caddisflies and the latter moths and butterflies. Both orders produce flying insects with scaled wings.
Trichopteran order insects appear holometabolous in the larval stage. This means that they possess upper and lower body parts that mirror one another. Following metamorphosis, the adults reappear with long thin wings, threadlike filiform antennae, and compound eyes. Adults also grow hair all over their bodies including their wings and their legs.
For most trichopterous species, coloration is dull when compared to other insects such as the closely-related butterflies or dragonflies; however, a few trichopterous insects do possess vivid coloration. The appearance of the dimmer species may help to protect them from enemies as they fly during the night.
Also, in some trichoptera species, the antennae may grow as much as three times the length of their front wings, whereas in other groups the antennae are shorter than the front wings.
Adult trichopterous insects do not eat, which may be why their mouthparts are relatively small, suited for liquid nourishment, or simply do not function. Larvae, on the other hand, have completely functional mouthparts and feed frequently. According to for Texas Insects, trichopterous larvae are able to construct webs made of silk and use them to capture food. They also use the silk when building cases for homes.
According to WhatBugIsThat, trichopterous insects may copulate as they fly or while stabilized on the ground or on certain types of plants (riparian vegetation). This insect is oviparous — the female releases fertilized eggs that must develop and hatch on their own. Females normally drop the eggs into or near waters in areas they frequent. Their metamorphic stages are complete, progressing from egg to larva to pupa to adult.
Trichoptera larvae look somewhat like caterpillars. They live in water, and thus must construct homes to shield themselves from enemies. They make their homes, or cases, from various materials such as sand, stones, plants, and debris. They use self-produced silk to adhere the cases together. Their ability to embed themselves in shielding cases is what earned the order its nickname. The term caddis means case. In addition to shielding themselves in their portable cases, larvae find food by scavenging and may feed from plants or animal remains.
When they reach their pupa stage, trichoptera embed themselves by wrapping silk around their bodies. At the end of the pupa stage, the larvae turned pupae cut through their casings with their mandibles and emerge as adult insects.
At night, adult trichoptera insects fly toward lighting and can be seen encircling outdoor light bulbs. Some insects of this order are nocturnal while others are diurnal. In addition to freshwaters, trichopterous insects frequent saline waters along coasts and streams.
Fish in the waters that trichoptera insects frequent are happy to eat the insects. For this reason, humans use the insects for fishing.
Related insect orders
As far as classification goes, trichoptera are more closely related to the lepidoptera order than it is to any other group of insects.
Adults in the trichoptera order only survive for a week or two after mating. Likewise, their lives are cut short whenever food is so scarce they cannot find anything to eat. Despite their shortened life spans, caddisflies continue to represent one of the largest aquatic insect orders.