1906 



ENTOMOLOGICAL SOCIETY. 



Ill 



THE LOCTTST MITE. 



By T. D. Jarvis, Ontario Agricultural College, Guelph. 



During the past summer the Locust Mite {Tromhidium locustarmn, 

 Eiley) has been very common at Guelph, especially on the Red-legged Lo- 

 cust {Melanoplus femur-rubrum) , but a few specimens have also been found 

 upon the Two-striped Locust (Melanojflus bivittatus). The mite is most gen- 

 erally found attached to the base of the second pair of wings, although it is 

 also found on the wing itself, and on any other part of the body where it 

 cannot be readily detached by the locust ; a favourite position upon the body 

 is between the segments of the thorax and abdomen, and also behind the 

 upper joints of the legs ; in such positions their only means of attachment 

 to their host is apparently by their mandibles. 



The j^oung mites are nearly spherical, and look very much like the eggs 

 of insects (Fig. 32, b). The mite sucks the blood of its host until it reaches 

 maturity, during which time it often becomes so swollen wdth food that its 

 legs are rendered very inconspicuous (Fig. 31, a). As many as five of 

 these young larvae have been found upon a single locust. 



The adult mite is of a bright crimson color and about one-eighth of 

 an inch long (Fig. 31, c, d). When full-grown it passes to the ground, where 

 it remains over winter. Dr. Riley, who has studied the life-history of this 

 mite, states that the eggs are laid an inch or so under the ground in clusters 

 containing between 200 and 400. Early in the spring from these eggs emerge 

 the young mites, which, upon reaching the surface of the ground, attach 

 themselves to their hosts. These little mites render good service in checking 

 the spread of the locusts, as almost every locust upon which one is found ap- 

 pears to be more feeble and sickly than those which have not been attacked. 



Fig. SI^Trombidium Locustarum — (a) mature larva when about to leave the wing of a 



locust ; (6) pupa ; (c) male adult fresh from the pupa ; (d) female— the natural sizes are 



indicated by the short lines on the right (e) palpal claw and thumb (/) pedal 



claws ; (g) barbed hair ; (ft) the striations on larval skin (after Riley. ) 



THE OYSTER-SHELL BARK LOUSE. 



By T. D. Jarvis, Ontario Agricultural College, Guelph. 



The purpose of this article is to place before the fruit-growers and all 

 interested in practical entomology, the main facts regarding the life-history, 

 habits and appearance of the Oyster-shell Bark Louse Scale, and of the scales 

 which are often mistaken for it. The damage done bv this scale of late 



