T. onustus is also distinguished from other relatives by its distinct life cycle patterns in which spiderlings emerge in either late summer or early spring.

It is relatively morphologically homogeneous genus, with synapomorphies that include circular scopula hairs (when viewed as a cross section), bulbuses that are subequal in length and width, disk shaped tegulums, sperm ducts that follow a circular peripheral course through the tegulum, and a lack of conductors and median apophyses.

[6] The family Thomisidae encompasses over 2000 species of crab spiders including the common close relative of T. onustus, Misumena vatia, Thomisus spectabilis.

They stay in flower corollas and wait for insect prey including bees (Apoidea), butterflies (Lepidoptera), hoverflies (Syrphidae),[10] diptera, hymenoptera, and other spiders.

Honey bees, for example, will avoid resource (nectar) poor habitats as well as those with higher concentrations of crab spiders, preferring to frequent safer areas.

There were also dietary factors, such as different types of pollen and nectar, that could potentially increase the survival rate of these spiderlings by 1.5-2 times.

This gives them access to more abundant prey resources, allowing them to obtain sufficient energy reserves to hibernate in vegetation outside of the cocoon during winter months.

Unlike the more variable developmental stages of T. onustus, the period of the cocoon, or the time between the laying of eggs and emergence of spiderlings, is generally around one month regardless of season.

[8] T. onustus typically molt at regular intervals up to the third and sixth instars provided they obtain adequate nutrition.

While their crypsis is imperfect, meaning that they do not perfectly match flower color, making them slightly detectable, T. onustus generally suffer little from bird predation.

[16] Female aggressive mimicry provides camouflage from predators and works to fool insect prey, usually pollinators of flowers on which spiders reside.

Spiders are capable of mimicking chromatic contrast of different flower species, allowing them to be cryptic in the color-vision systems of both avian predators and hymenopteran prey.

When aiming to detect smaller targets and/or see over larger distances, birds and bees preferentially use achromatic vision (brightness) over color contrast.

The compound β-ocimene, produced by plants in both floral and leaf tissues, acts as an attractive signal for both T. onustus and pollinators.

This mechanism generates strong selection pressure on plants to develop a mutualistic relationship with T. onustus and suggests a key role for the spiders in the evolution of floral traits.

Yellow coloration is likely due to the presence of ommochrome compounds and/or their precursors, such as xanthommatin and 3-hydroxykynurenine, deposited on hypodermal layers, which lie above specialized guanocyte cells full of guanine crystals, which lead to light scattering.

White coloration is likely due to high concentrations of the transparent ommochrome precursor kynurenine and the reflection from guanine crystals.

These explanations account for human-perceived white to yellow changes via differential pigment deposition in the hypodermis, but do not explain variations in UV reflectance.

Guanine crystals, present in the hypodermis, strongly reflect UV light, and, as the only UV-reflective element in crab spider color schemes, are the key determinant of UV-coloration.

UV reflectance may have evolved through a change in the metabolic pathway that allowed for guanine crystal exposure through partially UV-transmitting hypodermis and cuticle.

As a whole, interactions between the cuticle, pigments, and/or crystals in the hypodermis that exist in variable oxidative stages, and guanocytes combine to produce changes in the observed reflectance spectrum of crab spiders.

Such background matching is common in many animals able to undergo reversible color changes (some fish, reptiles, amphibians, crustaceans and cephalopods).

The endocrine system is thought to mediate the transduction of environmental cues into the physiological response of color change.