So7ne Solitary Wasps of Texas. 9 



The cause of its death was easy to understand, as I found protruding 

 from the sides of its abdomen a number of the egg-cases above 

 mentioned. 



As regards the length of developmental periods, the above data 

 only give the total length of development as thirty-nine daj^s and 

 that of the egg and larva together twenty days. 



(b) Odyxerus Arvensis, Sauss. 



This species of Odynerus does not posssess the architectaral skill 

 of its cousin Just described. Its home is not such an elaborate 

 domicile, built, as it were, for show as well as for use, but consists 

 of any convenient crevice in a wall or fence-post. The* nest is 

 completed by closing the opening of the crevice with mud, much 

 after the fashion of Trypoxylon. I have made a few observ^ations 

 on two nests of this Odynerus; those on the conditions of the cater- 

 pillars found in the nests are of particular interest. In general, 

 the following facts do not justify Fabre's conclusions which he 

 based on the habits of 0. reniformis. 



At noon, August 4th, a female arvensis was closing her nest 

 in the niche of a brick wall. A few days before a Trypoxylon 

 had emerged from the very niche now intended to be the cradle 

 of another wasplet. I immediately opened the nest and drew out 

 eight caterpillars, all of which were alive, six of them, in fact, so 

 lively that they wriggled around in the small vial to which I had 

 transferred them. I found no egg at first, but, looking carefully 

 into the dark recess, I discovered the egg suspended from the 

 ceiling of the little room. After breaking the suspensory thread 

 with a knife and brushing the egg out, I placed it among the 

 caterpillars in the bottom of the vial. Verj' few wasps' eggs could 

 stand the rough handling which this egg received. The explanation 

 of its endurance lies in the toughness of its shell. The larva 

 hatched in two and one-half days, having shed a tough, translucent 

 shell which could safely be handled with a pair of forceps. After 

 fifteen hours the larva had attached itself to a writhing caterpillar 

 and had grown perceptibly. The remaining data are as follows : 



August 9. Five days after the nest was closed, two caterpillars . 

 have been devoured and the remaining six are still alive, of which 

 four move spontaneously. The wasp larva is as large as one of 

 the caterpillars. The larva takes a long rest this morning. 



August 10, 6 p. m. All parts of all the caterpillars have been 

 devoured. 



