10 



Maine Agricultural Experiment Station. 1919. 



cling to the plant and, as with other insects generally, the skin 

 splits along the middle line of the back and the body and legs- 

 are gradually withdrawn and the increase in size and resump- 

 tion of color takes place in a short time. 



Five distinct stages of the nymphs are recognized and this 

 seems to be the genenal rule for the Hemiptera, being the num- 

 ber noted in a large number of the species which have been 

 reared through the nymphal stages (fig. 2). 



No single individual has been carried from the first instar 

 through to the adult stage but numbers have been carried from 

 two to four of the instars in confinement and under observa- 

 tion so that it is possible to give a connected series of stages- 

 from the smallest found to the adult form. The time occupied 

 in the different stages has run from 5 to 8 days, averaging 6 

 to 7 days, and the total period of development from hatching 

 to adult stage must be about 30 to 35 days. 



The principal changes are in the increase in size and in 

 the growth of the wing pads which are entirely wanting in the 

 first, appear as faint enlargements of the meso-thorax in the 

 second instar, are fairly distinct on both meso- and meta-thorax 

 in the third, extend to the second abdominal segment in the 

 fourth and on to the middle of the fourth segment in the fifth 

 for the female and to the base of the fifth segment for the 

 male. There is considerable irregularity in development as in- 

 stars 1-4 and probably 5 with adults were taken June 23. 



Fig. 3. Miris dolabratus: genital segments: A, female; B, male of 

 fifth instar nymph; C, female; D, male of adult. From drawings by 

 the author. (Jour. Agr. Research). 



In the fourth and fifth instars the sexes are easily distin- 

 guished, males being slightly narrower, the abdomen with more 



