Calynda bicuspis, also known as the walking stick, is an insect in the order Phasmida that looks similar to a small, slender stick with legs, brown or green in color. Females can grow up to 12 cm and males can grow up to 17 cm. They are often found in Central America in Pacific lowland areas. They are herbivores with a wide range of food sources such as Cassiflora biflora, Lonchocarpus minimiflorus, Indigofera sp., and Guazuma unifolia. Rigorous competition between males for mates causes males to cluster near copulating females. Reproduction occurs sexually with larger females mating with larger males. Eggs are seed like in appearance and once hatched, nymphs are separated into two morphologies based on size. They have been documented to live up to one year (Windsor & Massey 1983).
This species can be found in Central America in the Chiriqui province on the western coast of Panama and in savanna habitats of the province Guanacaste, Costa Rica (Stål. 1875, Windsor & Massey 1983).
These large and conspicuous insects can easily be found at night on low shrubs in Pacific lowland areas (Windsor et al. 1995).
C. bicuspis are herbivores. Most Phasmids tend to have specific plant preferences but C. bicuspis seem to be exceptional in this regard, feeding on at least 12 host plants with more possible. Favorite food plants include Cassiflora biflora, Lonchocarpus minimiflorus, Indigofera sp., Guazuma unifolia, Mimosa pigra, and Gliricidia sepium. Because these insects are large and conspicuous, they feed at night when they are less likely to be spotted and predated.(Windsor & Massey 1983).
Research has documented a relationship with Ectatomma ruidum, the ponerine ant. Using mandibles, E. ruidum transports C. bicuspis eggs into their nests. The ants then remove and consume the egg capitulum without affecting egg viability, but also increasing their susceptibility to egg-parasitoid as the capitulum acts as a defense against parasitism. (Windsor et al. 1995).
During Costa Rica’s dry season this species largely occurs on swollen thorn acacias,Acacia collinsii and A. cornigera, occupied by the acacia ant, Pseudomyrmex beltii (Windsor et al. 1995). During the wet season, C. bicuspis can be found on nonant plants, Mimosa pigra, Indigofera sp., and Guazuma unifolia (Windsor et al. 1995).
Males have 2 appendages protruding from the end of their abdomen used as female claspers when they reach maturity. Copulating females reach 12.5 cm or longer and have ovipositors that extend at least 1 cm beyond the end of the abdomen. This ovipositor is used to flip eggs (Windsor & Massey 1983).
Eggs are seedlike in appearance, 1-2mm in length with gray or brown coloring. They are ovoidal, capped on one end, with longitudinal stripes. Between 70 and 150 days after oviposition, hatching occurs. Nymphs are classified in two different morphologies: short (11-12 mm) and long (15-17 mm). There appears to be no sexual dimorphism at the stage (Windsor & Massey 1983).
Reproductive males are found to be nearly twice abundant as mature females. Male populations tend to cluster near copulating females suggesting that there is rigorous competition amongst males for mates (Windsor & Massey 1983). They are active in all months of the year but are especially concentrated during the dry season on the Pacific Slope of Costa Rica.Activity drops during the end of the dry season (Windsor & Massey 1983).
C. bicuspis reproduces sexually at night and exemplify assortative mating in which larger females tend to mate with larger males. Using sharp hooks on their terminal abdominal segment, males dig into females’ intersegmental membranes on their 6th and 7th abdominal segments. Because competition for mates is high, often times males clasp the females for several days, riding “piggy back” and even feeding from their position on the rear of the female. Mature females continuously produce and disperse eggs. Using the ovipositor, they flip eggs so that they come to rest on the ground beneath the plant on which the female has been feeding on.Oviposition rates vary; they can lay anywhere between 1-12 eggs per day (Windsor & Massey 1983).
Live 6 months on average but have been documented to live up to 1 year (Windsor & Massey 1983).
C. bicuspis has been reported to be eaten by Trogon melanocephalus (Riehl & Adelson 2008).
