Vol. X\i.\| ENTOMOLOCIC \I. \K\YS. J_'5 



frequently destroying the whole of the leaf except the midrib. 

 The Gastroideas are so fond of these plants, and confine them- 

 selves so closely to them, that they might well be given the 

 common name of Dock Beetles. 



During my investigation of these Chrysomelids in their nat- 

 ural surroundings and in captivity, rhubarb was the only culti- 

 vated plant upon which I found that they would feed, though 

 I tested them with lettuce, radish, beet and other plant leaves. 

 They ate sparingly of the rhubarb leaves and readily left them 

 when given access to dock. 



Although they have well developed wings they never fly and 

 their protection from enemies is their color and habit of feign- 

 ing death. 



The female deposits her eggs, which are elongated and 

 of a dark-yellow color, in irregular masses on the under 

 side of the leaves. The number of eggs in these masses varies, 

 but is usually from thirty to forty. The eggs are always de- 

 posited during the day, the individual laying later each day 

 until the laying is quite late in the afternoon, then she begins in 

 the early morning once more. One especially productive fe- 

 male deposited a batch of thirty-four eggs in the early morning 

 and thirty late in the afternoon of the same day. but this was 

 an exception and the only instance in which I have known of 

 more than one batch of eggs being deposited during the same 

 day. Occasionally there are days of rest when no eggs are laid. 

 One female deposited thirty-three eggs on the fifth day after 

 reaching maturity, which shows how closely one generation 

 may follow another. The first generation of females, which 

 mature from pupae that have passed the winter in the ground, 

 is the most productive generation of the year. While the aver- 

 age number of eggs produced each day is less than the average 

 number produced by later generations, the adult life period, 

 and therefore the productive period, is longer than that of la- 

 ter generations. During the height of the season of oviposit- 

 ing, the abdomen of the female is so dilated that the elytra 

 stand at almost right angles to the body, the female at this time 

 being much larger than the male. At the end of the laying sea- 

 son the abdomen returns to its normal sixe. There are four or 



