For an organism to be classified in the animal kingdom it is necessary for that organism to be eukaryotic and multicellular. In addition, he must not be able to produce his own food (he must be heterotrophic), and must eat by eating food taken from the environment.
To be classified in the dilo arthropoda, the organism must have an external skeleton, a segmented body and articulated legs.
To be classified in the insect class, the organism must have a separate body in the head, chest and abdomen, have two antennae, two pairs of wings and three pairs of legs.
Photosynthesis gives the plant food/nutrients to be able to survive. They make their own food
A woodcutter could justify cutting trees for use say in a pioneering situation whereby the pioneer needs shelter and food so trees could be necessary to say construct a small log cabin and table for eating/preparing food at to ensure the survival of the pioneer.
Blowfly eggs can be found in moist areas of a body within 8 hours of death. However, it won't be until the 21st-24th day the pupa cases will split open and adult blowflies emerge.