SECTION VI. — NATURAL ENEMIES OV THE FROfxHOPPER. 83 



The fungus, which is one of the £/i^omop//^/«on^ce«, attacks the living 

 froghoppers by hyphae from a germinating spore entering the body 

 apparently either through a spiracle or throu^'li the thinner parts of the 

 skin. The mycelium gradually fills up the body and the insect becomes 

 lethargic and dies. The mycelium tlien appears on the outside of the 

 body piercing at first cliietly through the thin connective tissue between 

 the abdominal segments, and fastens the insect to the substratum. 

 In the exposed places the fungus begins to produce its characteristic 

 dull olive-green cylindrical spores, which are formed in chains on the 

 ends of special erect hyphie and are from 0-004.')-0"0070nuu. in length 

 and 0-0023-0-002.5 mm. broad. 



From the time of oi'iginal infection of tlie adult to the time of its- 

 death may be from two to six days and spores usually begin to appear 

 about two or four days after this. The insect when killed by this fungus 

 usually has the hind legs stretched out behind and crossing over one 

 another and is either in the axil of a leaf, or attached to the surface of a 

 leaf (usually on the upper surface) near its base (cp. symptoms of 

 Empusa fungus below). 



The fungus is very much more abundant on adult froghoppers than 

 on the nymphs and indeed in the fields I have found it extremely' rare 

 on the latter. Many thousands of infected adults have been seen in the 

 last four years, but less than one dozen infected nymphs. 



Gough (1911 B.) says he has not seen naturally infected nymphs 

 and he had great difficulty in infecting them artificially, chiefly he 

 believed owing to the protective froth, but Roier found that they could 

 be infected as well as the adults. 



Among the adults a very large proportion of the infected specimens 

 are females. The following figures show this. 



Locality. • Males. Females. 



(Urich B. D. A. XI. p. 360) 9 38 



Brechin Castle 19. XI. 18 3 16 



Caroni 29. X. 18 3 7 



Reform 18. IX. 18 . 9 20 



Total 24 81 



This may be due to the greater activity of the males causing the 

 spores of the fungus to be shaken off more readily. 



It has also been observed that the infected females have usually not 

 laid their eggs, a fact which considerably increases the practical value 

 of the fungus. On the other hand the specimens dead and dying 

 from the fungus fall an easy prey to predaceous ants and are often 

 carried away by them before they have time to dissemi nate their spores. 



The fungus usually appears in the fields in small quantities on the 

 adults of the first brood. The first specimen seen in the field in 1918 

 was on 12th June and in 1919 on 27th June. -On the second and third 

 broods however it is usually widespread and occasionally is responsible 

 for the death of the greater part of the brood. Its increase appears to 

 depend chiefly on the moisture present in the fields, and in [)eriods of 

 drought (e.g. the "Indian Summer", which sometimes comes in September 

 and October) it does not spread. This is possibly one of the ways in 

 which the rainfall brings about its important effect on the prevalence of 

 blight in the different seasons, {see ]). 96) 



The Green Muscardine fungus is not confined to Trinidad, but is 

 known throughout the world on many different hosts. 



