Megaloprepus caerulatus

Megaloprepus caerulatus

''Megaloprepus caerulatus'' is a damselfly of the Forest Giant family , found in wet and moist forests in Central and South America. It has the greatest wingspan of any living damselfly or dragonfly, up to 19 centimeters in the largest males. Its large size and the markings on its wings make it a conspicuous species; a hovering ''Megaloprepus'' has been described as a "pulsating blue-and-white beacon".

As an adult it feeds on orb-weaver spiders in the forest understory, which it plucks from their webs. It lays its eggs in water-filled holes in trees; males defend the larger holes as breeding territories. The naiad is a top predator in its tree-hole habitat, feeding on tadpoles and aquatic insects, including the larvae of mosquito species that are vectors of human disease.

''M. caerulatus'' is the only species in genus ''Megaloprepus''.
Blue-winged helicopter (Megaloprepus caerulatus) Canopy Tower, Panama. Dec 31st, 2018 Geotagged,Megaloprepus caerulatus,Panama,Winter


''Megaloprepus'' avoids flying across large clearings that lack shaded perches, and has poor flight endurance, achieving a maximum distance of less than 1 km when experimentally released over water. This may limit its dispersal ability, making it particularly vulnerable to habitat fragmentation. While it can breed in secondary forest, it is less common there than in old-growth forest, even when the two are adjacent. Since ''Megaloprepus'' reduces the number of adult mosquitoes that emerge from tree holes it inhabits, and some of the species it preys on are important disease vectors, its conservation may have human health implications.


Most tree holes contain less than a liter of water, but some can hold as much as 50 liters. Male ''Megaloprepus'' defend these larger holes as breeding territories, mating with females who come to the tree hole to oviposit.

Several factors make large tree holes more valuable to ''Megaloprepus'' than small ones. Not only can their greater volume accommodate more naiads at a time, they have a higher density of prey in the form of tadpoles and mosquito larvae; this allows the naiads to grow more rapidly and reach adulthood sooner. In forests with a dry season, larger tree holes can last nearly a month longer before drying out completely. As a result, large tree holes can produce three cohorts per season, totalling perhaps a few dozen new adults, while only one or two emerge from a small hole. Large tree holes also give ''Megaloprepus'' better chances of surviving to emerge if one of its slower-growing relatives in genus ''Mecistogaster'' is already present. In a tree hole small enough to be effectively patrolled by a single naiad, the first species to hatch is likely to eat all newcomers, but in a large one ''Megaloprepus'' can escape long enough to outgrow and eventually eat an older resident. Finally, probably due to the greater abundance of prey, larger tree holes produce larger males that will be better able to defend a territory themselves when they reach reproductive maturity.

A territorial male drives away other males from his territory by chasing and sometimes hitting them. He does not allow females to lay eggs in the hole he defends without mating with him first, but he does not pursue females who opt instead to leave the scene. The structure of the penis suggests that, as with many other odonates, male ''Megaloprepus'' are able to displace sperm from previous matings, ensuring the paternity of the eggs. For their part, females do not choose mates based on size, and will sometimes remate with smaller males who cannot take over a territory and instead adopt a satellite position nearby. At least some females will lay eggs in undefended tree holes before mating again.


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SpeciesM. caerulatus
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