The Citrus Leafminer (CLM), or Phyllocnistis citrella, is one of the many invertebrates that in its larval stage, damages citrus crops all over the world. From oranges to lemons, grapefruits to limes, this insect attacks the leaves of the citrus, forsaking the plant to infections such as citrus canker. The CLM larvae survives solely on the young leaves (especially under 4 years old) of the citrus plant, “mining” its way through each leaf and distorting or curling it as they go.


Infestations and foliar mining are most severe in late summer and early fall. CLM deforms leaves, reducing the photosynthetic capabilities of the plant. From an aesthetic and marketing concern, it is especially problematic in citrus grown for the fresh market, since CLM can also impair the fruit rendering it unmarketable or steeply discounted.

Originally native to Asia, the CLM made its way around the world, landing in Florida in 1993 and subsequently in California in the mid-1990s. A full grown CLM is about ¼” long, and is a light-colored moth. However, the adults are not dangerous to the citrus plant. After the female CLM lays her eggs under a leaf, the larvae are the ones that slowly destroy the plant.

CLM is usually followed by broad spectrum spraying to combat asian citrus psyllid, which is evidenced when monitoring using lures. Careful monitoring with pheromone-baited traps is essential for detecting the presence and magnitude of target pest and other secondary pest populations. Recently, Alpha Scents has created a product called MalEx™, which combines the best aspects of two technologies: pheromone attraction and traditional chemical insecticides. The resulting product provides pest control that is effective, selective and residue-free. Each 50 microliter droplet contains Imidacloprid, a potent knock-down insecticide, and a synthetic version of the pheromone released by a female moth to attract or "call" a mate.

The attractant and insecticide are combined in a UV-absorbing carrier material that provides a slow, uniform release of the pheromone. Male moths are inevitably attracted to the small droplets of MalEx, which they attempt to mate with. Any contact with the product kills or disables them, thus preventing mating and subsequent egg-lay and larval infestation.


MalEx uses pheromones as they were intended to be used: to attract males. First, they simply and biologically attract the male, and then, the insecticide component of MalEx does its job, and takes the male out of the mating cycle. The insecticide can be found in every droplet, it does not contaminate the ground or the fruit, it is not harmful to humans, nor does it threaten beneficials. Other pests are not attracted to MalEx, making it a great example of integrated pest management that does not hurt the ecosystem.


MalEx has proven effective in field trials in Florida, Texas and California. MalEx has resulted in outstanding control of Citrus Leafminer when used as a stand-alone method or as part of an IPM program. It substantially reduces or eliminates supplemental insecticide use.