No. I.] CONTRIBUTION TO INSECT EMBRYOLOGY. 35 



7. TJie Development of Orchelivmvi vidgare. 



This Locustid oviposits like many of the smaller members 

 of the family in the pith of dead plants. I found the eggs in 

 Ohio during the last days of September in the stems of the 

 wild lettuce {Lactrica canadensis), so common along the edges 

 of fields and thickets, and in the petioles of the common elder 

 {Sambucns canadensis). Oviposition probably takes place in 

 the beginning or towards the middle of September. In the 

 case of Lactnca and a few other plants which I did not identify, 

 the insects had invariably selected for oviposition the main 

 stem of the flower-panicles. From base to apex this portion 

 of the stem was punctured at intervals, and a single o.g'g 

 thrust into the pith a short distance above each orifice. It 

 is an easy matter to recognize the punctures by the little tufts 

 which the insect evidently gnaws from the woody fibre, before 

 inserting its scimeter-shaped ovipositor. Great care'must be 

 taken in splitting the stem, so as not to tear or cut the eggs 

 which adhere very firmly to the pith. 



The eggs are larger than those of XipJiidiuni ensiferum, 

 being fully 6.-6.25 "^"^- ^orig. In shape they are very similar 

 to XipJiidium eggs except that the sides are compressed. 

 In the fresh state they are smooth and opaque, and of a 

 pale drab or bluish tint. In this respect, as also in the 

 flattening of their lateral faces, they form a transition to the 

 eggs of our larger Locustidas, e. g. Cy^'topJiyllus concavus, 

 AviblycorypJia uJilerii and Microcentrimi rctinervis} The 

 chorion is not readily wetted with water, but like that of 

 the Xiphidimn Q.gg, immediately becomes transparent when 

 immersed in alcohol. The outer envelope is then seen to have 

 a yellow tint, deepening into brown at the poles. 



As would be expected from its close systematic affinity the 

 embryonic development of OrcJielinium does not differ much 

 from that of XipJiidiwn. I have not seen all the stages, nor 

 have I, as yet, sectioned any of my material, but the stages 

 which I have examined are essentially the same as those 



1 For a description of the eggs of these species see an article on Orthoptera, by 

 Prof. C. V. Riley, in the Standard Natural History, Vol. II. pp. lSS-189. 



