While adult Mexican bromeliad weevils feed on bromeliad leaves and sometimes the inflorescence (flower stalk), it is individuals of the immature stage (the larvae) that kill the plant, by mining into the meristemmatic (growing) tissue. They may tunnel deep into the base of the plant, destroying most of the central stem and leaf tissue. As a result, the plant separates from its roots on the tree, falling to the ground and dying.

The most obvious symptom of weevil infestation is the decomposition of leaves at the base, with the middle of the plant becoming so loose it can easily be removed. Additional symptoms include adult feeding marks on leaves, browning of leaves as a result of weevil feeding at their base, and a clear, gelatinous material sometimes produced by the plant, probably in defense.

Where bromeliads are found in abundance it is not unusual to see a few of them scattered on the ground. They are mature plants that have died and fallen naturally, or more likely plants of all ages that have fallen together with the tree branches to which they are attached, especially after a heavy storm. Although they are healthy, bromeliads fallen with tree branches do not usually survive for long, because on the ground they are exposed to foraging by rabbits, squirrels and possibly deer.

The picture during an attack of the Mexican bromeliad weevil is very distinct, however. The ground may be filled with fallen bromeliads with open holes at the base instead of roots. Under the most severe infestations, thousands of Tillandsia plants have been seen to litter the ground. Within a few months to a few years, entire populations of some areas have disappeared.

The weevil has had the greatest effect on populations of Tillandsia utriculata in Florida. Adult weevils apparently prefer to lay their eggs in larger plants, resulting in a decline in the breeding populations of the bromeliads. When the weevils have killed all of the large plants in an area, they remain until the smaller plants reach breeding size, subsisting on smaller, less preferred species like Tillandsia balbisiana, Tillandsia flexuosa or Tillandsia paucifolia.

In Veracruz, the Mexican bromeliad weevil's homeland, Tillandsia utriculata reproduces vegetatively and is thus able to produce offsets when under weevil attack. It does not do so in Florida, and seeds are not released until the plant is beginning to die, so infested Tillandsia utriculata in Florida are not usually able to reproduce. This species takes many years to reach reproductive maturity, and the selective destruction of large individuals has caused its populations to suffer heavy losses in Florida.

Tillandsia fasciculata, which can produce vegetative offsets in Florida, is somewhat more resistant to the weevil than Tillandsia utriculata. Although it is more abundant in some natural areas than Tillandsia utriculata, it is often attacked less frequently, only suffering heavy damage when there are few or no large Tillandsia utriculata plants left.

The Mexican bromeliad weevil is currently attacking five species and one hybrid of native bromeliads in Florida, four of which appear on the state's list of threatened and endangered species. Two of those (Tillandsia utriculata and Tillandsia fasciculata) have been listed as endangered as a direct result of weevil destruction. The weevil is likely to attack Guzmania monostachia and the three species of Catopsis if it reaches their habitats, since it has been observed to feed on several species of Guzmania and Catopsis under greenhouse conditions. It has not and is not likely to attack the five most common species of bromeliads in Florida, because their small size does not provide enough material for development of weevil larvae. See Threats to Florida's Native Bromeliads for endangered/threatened status of each species.

In addition to threatening populations of native bromeliads in natural areas of south Florida, the weevil has been observed to attack 11 genera of imported cultivated bromeliads. Bromeliad growers and collectors routinely apply pesticides, keeping weevil populations below damaging levels. However, the weevil's effect on the environment of south Florida makes the need to manage its populations in natural areas urgent. Management Options for the Mexican Bromeliad Weevil explains the management strategy being implemented.

• Biology of the Weevil Metamasius callizona, from Weevils That Eat Bromeliads



• Mexican Bromeliad Weevil, from Featured Creatures



• Bromeliad Weevil Research in Florida