even survive the winter. They do not create gills; instead, the cap bottom is covered by an initially soft, white hyphen fungus, also known as a subiculum. Early on the mycelia becomes denser and takes on a white-grey colour. The perithecia are created after about 10–14 days. Perithecia are fruit bodies of the Hypomyces and other sac fungi, in which the spindle-shaped asci are produced. Besides L. deterrimus, L. deliciosus and L. sanguifluus can become infested, rarely other milk caps. Hypomyces lateritius, H. ochraceus, H. rosellus, H. odoratus, among other Hypomyces species live parasitically on different milk caps and brittlegills as well as on the fruit bodies of species from other genera. Importance Edibility Lactarius deterrimus is an edible mushroom, but is much less appreciated than the similar L. deliciosus. The first tastes slightly bitter and is often infested by maggots. Like L. deliciosus, this fungus is mainly stir-fried in butter or oil; if it is cooked in water, the flesh becomes very soft. Young fruit bodies can be also pickled, or dried for later use. As the fungus is often heavily infested by maggots, skilled mushroom pickers prefer young fruit bodies. The urine discolours to red if a large amount of milk caps are eaten, but this is entirely harmless and is not evidence for an impairment to health. The red-coloured azulene compounds, ingested with the mushroom food, are more or less excreted with the urine. Contents The milk cap's fruit bodies have a characteristic orange milk juice (latex). The guaiane sesquiterpenes are responsible for the orange colour. Sesquiterpenes are terpenes composed of three isoprene units and therefore have 15 carbon atoms. Sesquiterpenes are widely distributed in nature and are found in plants as well as animals, for example in the juvenile hormone of insects. Plants use sesquiterpenes as a defense compound against insects. According to some studies, sesquiterpenes have antibiotic, anticarcinogenic, or immunostimulant effects. Young, uninjured fruit bodies of L. deterrimus have sesquiterpenoides in the form of fatty acid dihydroazulene-esters. About 85% of the yellow-coloured dihydroazulene are esterified with stearic acid and about 15% with linoleic acid. If the fruit body is injured, the free sesquiterpene – a dihydroazulene alcohol – is released enzymatically. Several products are produced from it through oxidation: the yellow-coloured aldehyde delicial (1-formyl-6, 7-dihydro-4-methyl-7-isopropenylazulene), the purple-coloured aldehyde lactarovioline (1-formyl-4-methyl-7-isopropenylazulene), and the blue-coloured alcohol deterrol (1-hydroxymethyl-4-methyl-7-isopropenylazulene). The milk is first maroon through mixing with the