Bog Myrtle/Myrica Gale
Myrica gale is a species of flowering plant in the genus Myrica, native to northern and western Europe and parts of northern North America. The foliage has a sweet resinous scent, and is a traditional insect repellent, used by campers to keep biting insects out of tents.It is also marketed by Totally Herby of Scotland  as an insect repellent, and by The Highland Soap Company  as a soap.In Scotland it has been traditionally used to ward off the dreaded midge.Sweet Gale can grow in a narrow band in the intertidal zone, especially if it has some logs, washed down into the estuary on which to establish itself. It is a favorite food of beavers and low beaver dams can be found in the intertidal zone if sufficient sweet gale is present. The ponds thus formed are often completely submerged at high tide but retain water at low tide and provide deep enough water to provide a refuge for fish, including juvenile salmon where the water is too deep for predation by wading birds. Thus the presence of Sweet Gale can enhance salmon recruitment. Myrica gale is listed as an abortifacient and, therefore, should not be consumed by women who are, or might be, pregnant. wikipedia
Swedish scientists have found that Achillea_millefolium/ yarrow extract repels mosquitoes.
A Thai study found both clove oil and celery seed extract to be effective mosquito repellants:
Carvacrol Carvacrol inhibits the growth of several bacteria strains, e.g. Escherichia coli and Bacillus cereus. Its low toxicity together with its pleasant taste and smell suggests its use as a food additive to prevent bacterial contamination.
The cause of the antimicrobial properties is believed to be disruption of the bacteria membrane.
It is a potent activator of the human ion channels transient receptor potential V3 (TRPV3) and A1 (TRPA1).
Physiology of TRPV3 channel: TRPV3, is a human gene encoding the protein of the same name.
The TRPV3 protein belongs to a family of nonselective cation channels that function in a variety of processes, including temperature sensation and vasoregulation. The thermosensitive members of this family are expressed in subsets of sensory neurons that terminate in the skin, and are activated at distinct physiological temperatures. This channel is activated at temperatures between 22 and 40 degrees C.
The TRPV3 channel is widely expressed in the human body, especially in the skin in keratinocytes, but also in the brain. It functions as a molecular sensor for innocuous warm temperatures. Mice lacking these protein are unable to sense elevated temperatures (>33 °C) but are able to sense cold and noxious heat. In addition to thermosenstation TRPV3 channels seem to play a role in hair growth because mutations in the TRPV3 gene cause hair loss in mice. The role of TRPV3 channels in the brain is unclear.
The TRPV3 channel is directly activated by various natural compounds like carvacrol, thymol and eugenol. Several other monoterpenoids which cause either feeling of warmth or are skin sensitizers can also open the channel.
Herbal insect repellents (caution, see medical information for possible side-effects)
* Achillea alpina (mosquitos)
* alpha-terpinene (mosquitos)
* Basil Further information: Ocimum basilicum
* Callicarpa americana (Beautyberry)
* Camphor (moths)
* Carvacrol (mosquitos)
* Castor oil (Ricinus communis) (mosquitos)
* Catnip oil (Nepeta species) (nepetalactone against mosquitos)
* Cedar oil (mosquitos)
* Celery extract (Apium graveolens) (mosquitos)
* Cinnamon (leaf oil kills mosquito larvae)
* Citronella oil (repels mosquitos)
* Clove oil (mosquitoes)
* Eucalyptus oil (70%+ eucalyptol), (cineol is a synonym), mosquitos, flies, dust mites)
* Fennel oil (Foeniculum vulgare) (mosquitos)
* Garlic (Allium sativum) (rice weevil, wheat flour beetle) (NB: a dose similar to the one as a food ingredient should be used for the time being)
* Geranium oil (also known as Pelargonium graveolens) , 
* Lemon eucalyptus (Corymbia citriodora) essential oil and its active ingredient p-menthane-3,8-diol (PMD)
* Lemongrass oil (Cymbopogon species) (mosquitos)
* Marigolds (Tagetes species)
* Marjoram (Spider mites Tetranychus urticae and Eutetranychus orientalis)
* Neem oil (Azadirachta indica) (Repels or kills mosquitos, their larvae and a plethora of other insects including those in agriculture)
* Peppermint (Mentha x piperita) (mosquitos)
* Pennyroyal (Mentha pulegium) (mosquitos, fleas), but very toxic to pets.
* Pyrethrum (from Chrysanthemum species, particularly C. cinerariifolium and C. coccineum)
* Rosemary (Rosmarinus officinalis)  (mosquitos)
* Spanish Flag Lantana camara (against Tea Mosquito Bug, Helopeltis theivora) 
* Solanum villosum berry juice (against Stegomyia aegypti mosquitos)
* Tea tree
* Thyme (Thymus species)(mosquitos)
Also note that chimps consume noxious herbs to remove stomach parasites, capuchin monkeys rub citrus rinds on their backs to protect against insects, and spider monkeys use twigs/chewed foliage as body rubs. http://dsc.discovery.com/news/2009/07/31/spider-monkey-scratcher.html
Butterfly wings & typhoon probability
These proponents of chaos theory never mention that flying insects/birds/bats cause stratified gases in sub-canopy humid rainforests to mix, improving photosynthesis & respiration efficiency.
Ants & plants: plants control guardian ants with chemicals, repellants & food
ants & plants
Cycads (pre-conifers) & thrips (ant-like), chemicals attract & repulse, push-pull pollination
flower color changes