19?1.] FROGHOPFEB BLIGHT IN TBIMDAD. 57 



THE ENEMIES OF THE FEOGHOPPER. 



The chief enenij- of the eggs is the Vermilion Egg-parasite {OUgosita 

 giraulti), a minute red Chalcid. Its hfe cycle is about thirty days and 

 it can breed during most of the dry season when the froghopper itself is 

 inactive. It is almost certainly native to Trinidad and is not likely to 

 increase much above its present limits. It probably has some other 

 host in Trinidad. Abroad it is known from British Guiana to Costa Rica 

 on various species of froghoppers. 



The Trash-Coloured Egg-Parasite {Paraplirlimis tomasindis) was 

 recorded in 1913 as destroying froghopper eggs, but this habit has never 

 been confirmed and it is doubtful if it is of any value as a control. 



In Panama a new egg-parasite of the genus Anagrus was found. 



Thrips of the genus Haplothripn and ants are known to destroy the 

 eggs, and eggs are sometimes found filled with a fungus which may have 

 killed them. 



The nymph is eaten by some birds but the frothy covering seems to 

 render them unpalatable to most. They have been found in the stomachs 

 of the Boat-tail (Qnisqualus lugnbris), the Golden-head {Agelaius 

 icterocephalus) and the i\[anicou-Bird {Geofhijljus acquinodialis). 



The Syrphid fly is the most important enemy of the nymph. It lays 

 its eggs in the froth of the froghopper, and the maggot, which hatches 

 in about two days, destroys the nymphs by piercing their skin and 

 sucking out the juices. One maggot may destroy BO-40 nymphs. The 

 larval stage lasts nine or ten days and the pupa about the same time. 

 The complete cycle takes about three weeks. In the moister parts of the 

 island the fly breeds throughout the year, but in the cane fields it is not 

 found in the dry season and is seldom common before the second or 

 third brood of froghoppers. It ranges outside Trinidad from Mexico to 

 Brazil on various species of froghoppers. 



An attempt was made by Kershaw and Guppy in 1914 to breed large 

 numbers of this fly through the dry season so that they could be 

 liberated to destroy the first brood in the following year. Owing to the 

 difficulty of obtaining, dvn-ing the dry season, enough nymphs for the 

 syrphid maggots to feed on, the work had to be abandoned. 



Another parasite of the nymph is the Mermis worm, a Nematode 

 which is occasionally found coiled up in the abdomen of the nymph or 

 adult froghopper. It is not common and nothing is known of its 

 life history' or habits. 



The Green Muscardine fungus is only rarely found on the nymphs in 

 the field. 



The adult froghopper has a long list of parasites and enemies. 

 Seventeen different birds have been proved to eat adult froghoppers 

 One of the most important of these is the Scissors-tail Fly-Catcher 

 which migrates to Trinidad from the mainland of South America^ 

 at the beginning of each wet season, arriving in May or June and 

 leaving in October and November. 



