Chapter 9: Entomology Flashcards
What is an insect? Is it the same as an arthropod?
Insects are the largest group of arthropods. Insects have six legs and a three-segment body. Arthropods contain many subgroups, including insects, arachnids, centipedes, millipedes, and crustaceans.
How many kinds of insect development are there and what are they?
There are three patterns of growth for insects.
The first is ametabolous metamorphosis (without change). In this type, the eggs yield immature forms that look like smaller forms of the adults. The juveniles eventually develop in size and mature sexually but otherwise undergo little structural change.
E.g. Wingless insects (apterygota)
The second type is paurometabolous metamorphosis (gradual). The hatchlings emerge in a form called a nymph, which resembles a wingless erosion of the adult version of the species. Nymphs grow by moulting (shedding their skin), and each molt produces a new instar or growth phase.
E.g. cockroaches (Blattaria) and various predatory bugs (Hemiptera)
The third type is holometabolous metamorphosis (or complete) where the adult lays an egg (oviposits) or deposits a larva (larvaposits) onto a food source. The larvae start eating or hatch from the egg and then begin eating immediately and increase in size by molting from the egg and increase in size by molting through instars. The larval form is very different from the adult form. The larvae transition into an inactive phase, called the pupal stage. The pupa is a hardened outer shell or skin that protects the larva while it undergoes the final growth stage.
E.g. Butterflies and flies (Diptera)
What is the protective outer covering on an insect called?
Insects have an external skeleton, called an exoskeleton, composed of chitin and protein.
What is an instar?
An instar is a phase of growth.
What is taxonomy?
Taxonomy is the science of identifying and classifying organisms.
What are the categories, in order, used to describe an organisms taxonomy?
The taxa, or related groups, is broken into kingdom, phylum, class, order, family, genus, and species.
In “PMI in Hawaii,” Lee Goff used a particular fly, Chrysomya rufifacies, in his PMI estimate. What are the words C. rufifacies?
Chrysomya is the genus and rufifacies is the species.
What does necrophilous mean?
Necrophilous insects are dead loving insects or those associated with decomposition.
What are the uses of forensic entomology?
Forensic entomology can determine the postmortem interval, provide information about the circumstances surrounding death, if the body has been moved. They are also helpful in telling the drugs, toxins, other substances that are in the body at the time of death. Also can give indications of locations.
What is the difference between insects that larvaposit and those that oviposit?
Larvapositing is exclusive to insects that deposit a larva instead of an egg. Larvapositing eggs are exclusive to holometabolous metamorphosis.
Ovipositing is exclusive to insects that deposit an egg instead of a larva.
Name three factors that go into calculating a PMI.
The insects, or their young, that inhabit a dead body
The temperature of the area
The humidity of the area, weather etc
What are the four kinds of species that can be found on a dead body?
Necrophagous species: feed on the carrion
Diptera, coleoptera
Predatory and parasitic species: insects that prey on other insects, including the necrophagous ones
Coleoptera, some diptera
Omnivorous species: may eat material from the body, other insects, or whatever food source presents itself
Wasps, ants, some coleoptera
Incidental species: uses the cadaver as an extension of their habitat
Spiders, butterflies, collembola
How many waves of insect invasion are there on a dead body?
After the body has been dead for 1-2 days, it will have infestations of mainly blowflies. (They are attracted to a corpse almost immediately) There are about 2-8 waves of insects on a body.
Many environmental factors such as if the body is buried or surface, the weather, humidity, temperature, amount of light, season, manner of death and more can influence the number, type, appearance, and life cycles of necrophagous insects.
What does necrophagous mean?
Necrophagous insects are those that feed on the carcass. Examples include diptera, coleoptera, silphidae, and dermestidae.
What are the larvae of necrophagous insects called?
The larvae of necrophagous insects are called carrion feeders.
