Definitions

Arachnids:

Arachnids are a class (Arachnida) of joint-legged invertebrate animals in the subphylum Chelicerata. All arachnids have eight legs, although the front pair of legs in some species has converted to a sensory function, while in other species, different appendages can grow large enough to take on the appearance of extra pairs of legs. The term is derived from the Greek word ἀράχνη (aráchnē), meaning “spider”.[2]
Almost all extant arachnids are terrestrial. However, some inhabit freshwater environments and, with the exception of the pelagic zone, marine environments as well. They comprise over 100,000 named species, including spiders, scorpions, harvestmen, ticks, mites and Solifugae.[3] (Wikipedia)

Capitulum

The head-like mouthpart apparatus of a tick, including the palpi, mandibles, and hypostome. (Wikipedia)
Coxae:
The basal segment of a limb of various arthropods (insects and spiders, for example). (Wiktionary)
Molting:
The process of shedding or losing the exoskeleton of a tick.  Since the cuticula of these animals often forms an inelastic exoskeleton, it is shed during growth and a new, larger covering is formed.[2] The remnants of the old, empty exoskeleton are called exuviae.[3]After moulting, an arthropod is described as teneral, a callow; it is “fresh”, pale and soft-bodied. Within one or two hours, the cuticle hardens and darkens following a tanning process similar to that of the tanning of leather.[4] It is during this short phase that the animal expands, since growth is otherwise constrained by the rigidity of the exoskeleton. (Wikipedia)
Nymph:

In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis (hemimetabolism) before reaching its adult stage.[1]Unlike a typical larva, a nymph’s overall form already resembles that of the adult. In addition, while a nymph moults it never enters a pupal stage. Instead, the final moult results in an adult insect.[2] Nymphs undergo multiple stages of development called instars. (Wikipedia)

 

Nymphal Instar:

An instar (from the Latin “form”, “likeness”) is a developmental stage ofarthropods, such as insects, between each molt (ecdysis), until sexual maturity is reached.[1] Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or changes in the number of body segments. Some arthropods can continue to molt after sexual maturity, but these subsequent molts are generally not called instars.

For most insect species the term instar is used to denote the developmental stage of the larval or nymphal forms of holometabolous (complete metamorphism) or hemimetabolous (incomplete metamorphism) insects, but the term can be used to describe any developmental stage including pupa orimago (the adult, which does not molt in insects).

The number of instars an insect undergoes depends on the species and the environmental conditions. Lower temperatures and humidity often slow the rate of development. (Wikipedia)

Larvae:

A larva (plural larvae /ˈlɑrviː/) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The larva’s appearance is generally very different from the adult form (e.g. caterpillars and butterflies). A larva often has unique structures and organs that do not occur in the adult form, while their diet might be considerably different. (Wikipedia)

Permethrin:
Permethrin is a common synthetic chemical, widely used as an insecticide, acaricide, and insect repellent. It belongs to the family of synthetic chemicals called pyrethroids and functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to rapidly harm most mammals or birds, but is dangerously toxic to cats[1][2] and fish. In general, it has a low mammalian toxicity and is poorly absorbed by skin.[3]
Permethrin kills ticks on contact with treated clothing. A method of reducing deer tick populations by treating rodent vectors involves stuffing biodegradable cardboard tubes with permethrin-treated cotton. Mice collect the cotton for lining their nests. Permethrin on the cotton instantly kills any immature ticks that are feeding on the mice. It is important to put the tubes where mice will find them, such as in dense, dark brush, or at the base of a log; mice are unlikely to gather cotton from an open lawn. (Wikipedia)
Scutum:
 A scute or scutum (Latin scutum, plural: scuta “shield”) is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects. Scutes are similar to scales and serve the same function. (Wikipedia)

Spiracles:

Spiracles are openings on the surface of some animals that usually lead to respiratory systems. Insects and some more derived spiders have spiracles on their exoskeletons to allow air to enter the trachea.[4] In the respiratory system of insects, the tracheal tubes primarily deliver oxygen directly into the animals’ tissues. The spiracles can be opened and closed in an efficient manner to reduce water loss. This is done by contracting closer muscles surrounding the spiracle. In order to open, the muscle relaxes. The closer muscle is controlled by the central nervous system but can also react to localized chemical stimuli. (Wikipedia)

 

Spirochete:

Borrelia burgdorferi

Borrelia burgdorferi

Any of a group of spiral-shaped bacteria, some of which are serious pathogens for humans, causing such diseases as syphilis, yaws, Lyme disease, and relapsing fever. Spirochetes include the genera Spirochaeta, Treponema, Borrelia, and Leptospira.

Spirochetes are gram-negative, motile, spiral bacteria, from 3 to 500 micrometres long. Spirochetes are unique in that they have endocellular flagella (axial fibrils, or axial filaments), which number between 2 and more than 200 per organism, depending upon the species. Each axial fibril attaches at an opposite end and winds around the cell body, which is enclosed by an envelope. Spirochetes are characteristically found in a liquid environment (e.g., mud and water, blood and lymph).

Treponema includes the agents of syphilis (T. pallidum) and yaws (T. pertenue). Borrelia includes several species transmitted by lice and ticks and causing relapsing fever (B. recurrentis and others) and Lyme disease (B. burgdorferi) in humans. Spirochaeta are free-living, nonpathogenic inhabitants of mud and water, usually in oxygen-free regions.