32 



PROCEEDINGS OF THE NATIONAL MVSEUM. 



VOL. xxvni. 



Fii.. IS. — The larva (leptvs) of a Tko.m 



BIDIU5I. 



cause of the '" ervtliemii autiuniiale/' In parts of Germany a severe 

 infestation is known as " Staclielbecrkrantheit." In England and Scot- 

 land it is called the ' ' harvest mite "' and ' ' gooseberry bug. " In Mexico 

 red l)ugs are known as '" Tlalsahuate/' in Japan as ^' Akamushi,-' and iu 



parts of the West Indies as the "bete- 

 rouge." In all these countries they 

 have at times l)een a serious anno^'ance 

 to the peasantry and hindered or pre- 

 vented the harvesting of certain crops. 

 The female deposits the eggs in or upon 

 the ground, sometimes as many as -100 

 together. They are usually brown and 

 spherical, and were by some early writ- 

 ers considered to be fungi. The outer 

 ski n or chlorion soon splits, dividing the 

 ^gg into halves and exposing the pale 

 vitteline membrane. This stage is the 

 "deutovunr" of Claparede. 

 The newly-hatched larva is circular or ovoid in outline, with three 

 pairs of legs, each tipped with two or three prominent claws. After 

 becoming attached to the insect the larva becomes elongate and swollen 

 with food. AVhen full fed it drops oti', seeks shelter, and gradually 

 changes in shape, ])ut does not molt. The new parts are formed under 

 the Iftrval skin, which in a few weeks cracks 

 and discloses the adult TromhldluiK. 



The mature mite is not parasitic, but 

 wanders about feeding on small insects, 

 as plant-lice, young caterpillars, and one 

 species, T. Jocustaruin Riley, is known to 

 destroy a great many grasshopper eggs. 

 A French species has been found destro}'- 

 ing the I'oot-forms of the dreaded PhyJ- 

 hhvera. The adult hibernates in sheltered 

 places, or in the soil; the eggs are laid in 

 the spring, and there appears to be l)ut one 

 brood a year. Onl v a few forms have been 

 bred; the larva^ of one of them is common 

 on the house fly in autumn, and a similar 

 form occurs on mosquitoes. 



Our species are all practically congeneric, 

 ))ut those forms that liaAC two claws at the tip of the palpi fall in the 

 genus Mlcrotroiiihidruni Haller. Kolenati's genera Otony.^siis and 

 PiploriyHSus, parasitic on bats, appear to be larval Trombidions. The 

 genus Tromhklhon contains a great many species — in the United States 

 about ten. Several of our species are very common, and are often seen 



Fig. 49.— Tbumbidivm locustarum, 

 male. 



