Leaf miners are insects with a relatively short life cycle, typically requiring 21 to 28 days for development in warm environments. The time from egg deposition to adult emergence is about 19 days at a constant 25°C, with development rates increasing up to 30°C. However, temperatures above 30°C are unfavorable, leading to high mortality rates in larvae. The egg stage takes around 2.7 days at 25°C, followed by three active larval instars, which take 1.4, 1.4, and 1.8 days, respectively. The time spent in the puparium is approximately 9.3 days, and the adult preoviposition period averages 1.3 days. Development occurs within a temperature range of 6 to 10°C, though egg-laying requires temperatures around 12°C.

Life Stages:

• Egg: Eggs are deposited on the lower surface of leaves, typically in the middle, just beneath the epidermis. They are oval, measuring around 1.0 mm long and 0.2 mm wide, initially clear but turning creamy white.

• Larva: The larva is legless and initially colorless, turning yellowish as it matures. It lacks a strong tapering toward the head end, unlike many other fly larvae, and has a pair of spiracles at the posterior end. There are three larval instars, with the first instar measuring around 0.39 mm in body length, the second instar around 1.00 mm, and the third instar around 1.99 mm.

• Puparium: After the third larval instar, the larva leaves the leaf mine and drops to the soil to pupate. The puparium is oval, measuring 1.3 to 2.3 mm in length and 0.5 to 0.75 mm in width, and changes color from yellowish to brown over time.

• Adult: Adults live for about 13 to 18 days. Females cause damage to the foliage through feeding and oviposition, which results in stippling on the leaves, especially at the leaf tip and margins.

Damage and Host Plants: Leaf miners cause significant damage to plants by mining the leaves, destroying the mesophyll and affecting photosynthesis. The damage also leads to premature leaf drop, sun scalding of fruits, and increased vulnerability to bacterial and fungal diseases. The mine pattern is typically irregular, with a blotch-like shape near the end. The frass near the end of the mine becomes granular.

Leaf miners infest a wide variety of plants, including beans, carrots, cucumbers, eggplant, lettuce, melons, peppers, potatoes, and tomatoes. Flower crops like chrysanthemums, gerbera, and marigolds are also commonly affected. Numerous broad-leaved weeds, such as nightshade, Spanish needles, and pilewort, serve as suitable hosts for larval development.