[2][3] In Europe and New Zealand[4][5][6] the larvae are pests of plants in the order Brassicales, including arugula, brassicas, broccoli, Brussels sprouts, bok choy, cabbage, canola, cauliflower, horseradish, kale, kohlrabi, napa cabbage, nasturtium, radish, rapini, rutabaga, turnip, wasabi and watercress.

[11] Scaptomyza flava is Holarctic in distribution, commonly found across Europe, Asia and North America and only recently has been discovered in New Zealand, where it was first mistaken as a leaf mining agromyzid.

In captivity, the duration of the Scaptomyza flava life cycle is approximately three weeks, with an average egg to adult growth period of around 20.52 days.

The length of the life cycle is over two times as long as yeast-feeding Drosophila like D. melanogaster, a difference likely due to the fact that leaves are less nutritious[21] and mount a potent chemical defense response against the eggs and leaf mining larvae.

[8][22][23] Like other adult females in the subgenus Scaptomyza, have highly sclerotized (hardened and darkened) ovipositors valves that are studded with 20-30 tooth-like sensilla.

Generally, a male approaches a female and in a display of courtship flaps his wings and touches her body with his front legs.

The trophic level of S. flava is more similar to a fluid-feeding aphid based on highly depleted nitrogen profiles.

Some glucosinolates (aliphatic) break down into stable mustard oils (isothiocyanates), which persist in the environment (and are found in wasabi), but they are highly electrophilic, toxic molecules that rapidly bind to DNA and cysteine and lysine residues in cells.

[22] However, the glutathione S-transferase enzymes in the Scaptomyza species that feed on Brassicales are more efficient than any known from any animal at detoxifying mustard oils.

[12][28] Most species of Scaptomyza are not herbivorous and over half of all living species (but no known leaf-miners) are native to Hawaii where they have diverse life histories, from spider egg sac parasitoids to leaf breeding (feeding on microbes and even perhaps dead arthropods trapped on sticky surfaces[15][12]).

[12] Other species in the family Drosophilidae have a strong affinity for detecting the odors of yeast, a trait that S. flava has lost evolutionarily because its lineage has lost three genes encoding odorant receptors (ORs) that are known in D. melanogaster to be tuned to alilphatic esters produced by yeast.

[30] ORs encoded by recently duplicated Or67b genes that evolved rapidly in the S. flava lineage were found to be tuned to volatile mustard oils, which are emitted by wounded Brassicales plants.

This suggests that S. flava Or67b, when artificially expressed in a distant relative that feeds on yeast in rotting fruit, can result in an attraction behavior to mustard oils, possibly explaining how specialization on toxic plants can occur through simple genetic changes.

Most drosophilids, especially those associated with rotting fruit, encounter ethanol and have evolved mechanisms for tolerating and even using it to combat parasitoids.

[34] As a result, they mount a rapid chemical defense to render the food and habitat an inhospitable environment after wounding is detected.

[35] The species S. flava and S. nigrita have evolved the ability to partially metabolize the hydrolysis products of glucosinolates, which include the isothiocyanates, and are toxic chemicals synthesized by mustard plants and relatives as a defense mechanism.

Glucosinolates play a role in regulating stress-related genes in S. flava, which is different from the specialized systems that other herbivores have developed to bypass the toxic effect of the chemical.

[22] Scaptomyza flava adult females and larvae inoculate their host plants with bacteria to aid in the feeding process.

[36] The relative S. nigrita has a complex association with phyllosphere bacteria, that likely includes antagonisms, mutualisms, and commensalisms between the leaf miner and microbes.

Specific genetic changes that have evolved and are involved in the adaptation to feeding on living plants can be more easily identified as a result.