Trombidiformes 161 



5. Tetrapolipus Berlese, 1911 



Type. Tetrapolipus batocerae Berlese, 1911 



Discussion: These mites are parasitic on other arthropods. Locus- 

 tacarus trachealis Ewing is found in the tracheae of grasshoppers in 

 the United States and South Africa. Tetrapolipus rhynchophori Ewing 

 was taken from beneath the elytra of Rhynchophorus palmarum, a 

 palm weevil from Panama. Podapolipus reconditus Rovelli and Grassi 

 is to be found under the elytra of certain European beetles; Podapo- 

 lipus grassi Berlese, P. bacillus Berlese, and P. diander Volkonsky are 

 external parasites of grasshoppers. 



The most complete study of these mites has been made by Volkon- 

 sky 1940 on Podapolipus diander, a parasite of Locusta migratoria L. 

 in Algeria. Young females of the mites are usually found under the 

 posterior extension of the pronotum in the first three instars of the 

 grasshopper. In the fourth and fifth instars the mites attach and lay 

 eggs on the body under the rudimentary elements of the elytra and 

 wings. When the grasshopper molts, the immature mites that have 

 hatched from the eggs and the females that have not yet engorged and 

 oviposited leave the cast skin and attach to the host grasshopper again. 

 The adult grasshoppers harbor these mites in the folds between the 

 mesothorax and metathorax and on the parts of the thorax covered 

 with the elytra, on the underside of the elytra near the base, and along 

 the main veins of the wings, usually on the ventral side. The first-stage 

 females of the mites transform into adults. These adults mature and 

 produce parthenogenetically an egg from which a "small" male imme- 

 diately hatches. This "small" male mates with the parent female, and 

 the latter begins to lay eggs which hatch within five or six days to pro- 

 duce females and "large" males. These males are parasitic on the fe- 

 males, perforating the abdomen of the female mites and at times killing 

 them. These first-stage females attach to the intersegmental membranes 

 of the grasshopper, feeding by piercing the integument, and gradually 

 migrate toward the posterior segments and congregate at the genitalia. 

 Mites are spread from one grasshopper to another when the grass- 

 hoppers mate. If the temperature rises to about 80.6 F many of the 

 mites leave the host at night and crawl into crevices in the soil or to 

 the tips of grass blades, attempting to attach to any object with which 

 they come into contact. If they attach to Locusta migratoria the life 

 cycle is continued; otherwise they die. The mites may develop con- 

 tinuously during the summer and pass the winter as eggs or as first- 

 stage females attached to the grasshoppers. 



