Lakin Grasshopper

Grasshopper species diversity in the southwest U.S. presents enough of a challenge for the amateur naturalist, but then you have the Lakin Grasshopper, Melanoplus lakinus, that can apparently pass for several hundred species all by itself. That's an exaggeration, of course, but there is such great variability in the color, pattern, and wing length of this species that it is mind-boggling.

Lakin Grasshopper male

Lakin Grasshopper is often overwhelmingly abundant in disturbed habitats such as vacant lots and weedy fields and rangeland filled with its favorite host plants, members of the goosefoot family Chenopodiaceae. This includes Russianthistle ("tumbleweed"), kochia, and native saltbush (Atriplex spp.). It will also feed on various forbs and grasses such as lambsquarters, western wheatgrass, and downy brome. Despite high population densities in some years, it is seldom a crop pest.

Lakin Grasshopper female

This is a grasshopper of the Rockies and Great Plains, ranging from South Dakota and southern Minnesota south through western Iowa, most of Kansas, western Oklahoma, the west half of Texas, plus Nebraska, Colorado, New Mexico, and the eastern two-thirds of Wyoming, Utah, and Arizona. It also occurs deep into central Mexico.

Red form female from New Mexico

Melanoplus lakinus is a pretty "average" grasshopper. Adult males measure about 22 millimeters in body length, females 30 millimeters. Most specimens are short-winged as adults, but some are fully-winged. The overall color varies greatly from brownish or gray to green or even red. The tibia ("shin") segment of the hind leg is usually blue, armed with spines that are black or at least black-tipped. The inner surface of the hind femur ("thigh") is often reddish in part, especially along the bottom edge where the tibia folds into it. The top surface of the femur is most often marked with pronounced dark bands.

Green form female from Colorado

Dark bands on the abdomen, especially near the base, are helpful in recognizing the species in the field, but ultimately one has to examine the external genitalia of the male to confirm identification.

Ok, so how do you even tell apart the different genders? Below is an image that shows the male and female side-by-side, from the rear. The male is on the right. The female is on the left, but her abdomen is twisted to repel his advances, or accept his overtures, I'm honestly not sure which because I did not stick around long enough to see the outcome.

Male on right, female on left, rear view

The male's parts are pretty complicated, but you want to look at the shape of each "cercus," paired tail-like appendages. In the example below, we see that the cercus of M. lakinus is shaped something like a Hershey's candy kiss: broad at the base and tapered toward the tip. Next, take a look at the shape of the subgenital plate. It is best to view it directly from the rear, like in the image above. We can see it has a low, blunt tooth right in the middle. The supra-anal plate also offers species-specific details, but they are more difficult to discern, especially in images.

Anatomy of male M. lakinus

When two grasshoppers do get together, it looks like this:

Mating pair, male on top

Pretty kinky, almost literally! Mated females deposit clusters of eggs ("pods") in the soil by telescoping their abdomen as deep as it can reach. The eggs are held together by a kind of foamy secretion that hardens to protect the mass from environmental extremes. The eggs hatch in late May or early June, on average, the following year. In Arizona, where summer monsoons trigger hatching, emergence is usually in early July. The nymphs pass through five instars (an instar is the interval between molts), reaching adulthood in about a month.

Long-winged female from New Mexico

This year was a good one for the Lakin Grasshopper here in Colorado, and also in New Mexico, as heavy spring rains provided the nymphs with plenty of food after years of draught. The adults have hung around a long time, too. Just yesterday I spotted one basking on the sunny side of a building in our townhouse complex.

Sources: Capinera, John L. , Ralph D. Scott, and Thomas J. Walker. 2004. Field Guide to Grasshoppers, Katydids, and Crickets of the United States. Ithaca, NY: Comstock Publishing Associates (Cornell University Press). 249 pp.
Branson, David H. and Bethany Redlin (eds.). 2004. Grasshoppers: Their Biology, Identification and Management. 2nd Edition. US Department of Agriculture, Agricultural Research Service.
Grasshoppers of Colorado

Spider Sunday: Spider Sex Ed

Just to clarify, this lesson is for people, not spiders. Spiders already know how to do it. Wait, that didn’t come out right, either. What I mean is, this is a primer on how to tell spider genders apart, and show why it is so difficult to properly identify your average arachnid.

Mating Neriene sp. dome spiders, Arizona

Immature spiders cannot be identified to species (sometimes not even to genus) because they lack developed external genitalia that are species-specific. It is even more complicated than that because more “primitive” types of spiders don’t have complex genitalia anyway. Tarantulas, trapdoor spiders and their allies, collectively known as the Mygalomorphae, don’t have fancy equipment.

Next up on the ladder from mygalomorphs is another large clade called Haplogynae. The term has Greek roots and roughly translates to “half woman.” Among familiar haplogyne spiders are crevice weavers (Filistatidae), recluse spiders and their kin (Sicariidae), cellar spiders (Pholcidae), and spitting spiders (Scytodidae). Mature female haplogynes have a relatively simple genital opening known as the gonopore, accessed by the male through her “epigastric furrow.” The epigastric furrow is a simple transverse slit on the underside of the female’s abdomen.

Male spiders of all species do not have a penis, so they have evolved to use their pedipalps as intromittent sex organs to transfer sperm to the female. Pedipalps are the leg-like mouthparts nearest the spider’s face. The male spider prepares himself by spinning a small sheet of silk called a “sperm web.” He then extrudes seamen onto the sheet and sucks it up into a reservoir inside each pedipalp. He is now ready to go hunting for a mate. Males always wander to find a mate, even those species normally confined to webs.

Male mygalomorph and haplogyne spiders have no need for elaborate pedipalps because the female’s genital opening is correspondingly simple. Not so with the most highly-evolved spiders, the Entelegynae. Greek for “whole woman,” the term describes the much more complex genitalia of both genders. The overwhelming majority of non-fossil spiders fall within this group.

Sperm from the male goes into the female’s oviduct during mating in haplogyne spiders; and the sperm exits the same duct when the female lays her eggs. The sperm goes in one duct (copulatory duct) and out another (fertilization duct) in entelegyne spiders. Females of all types of spiders are capable of storing sperm from one mating for use their entire reproductive lives. This storage tank is called the spermathecae.

Epigynum of female Pirata piraticus wolf spider, Massachusetts

Female entelegyne spiders usually have a sclerotized (hardened tissue) “door” to their genitalia, located on the underside of the abdomen just above the epigastric furrow. This apparatus is called an epigynum (image above). It is usually composed of two openings, such that the structure has a symmetrical appearance. It is key to identifying many spiders to genus and species that otherwise look virtually identical to other, unrelated spiders.

The epigynum is more like a “lock” to the spider itself, as only males of the same species are able to mate with her. The male’s pedipalps are correspondingly complex, the “keys” to her “lock.” Male spiders that are one molt away from adulthood are termed penultimate and their pedipalps are swollen but not completely formed. The terminal segment changes radically with that last molt.

Pedipalp of male Bathyphantes sp. sheetweb weaver, Massachusetts

The image above shows the ventral (underside) view of the pedipalp of a mature spider. The dark, circular line is the “embolus,” the appendage that enters the female’s epigynum. The area behind the embolus is the “bulb” in which the sperm is stored. The bulb rests inside the cup-like dorsal plate called the “cymbium.” The pedipalp can also have various processes and projections on the cymbium and/or the patella or tibia segments.

Pedipalp of male Wadotes sp. funnel weaver, Massachusetts

Anyone who is serious about identifying spiders will not be able to avoid journal articles and books filled with images not of whole spiders, but their genitalia. Figuring out which end is up and exactly which parts the text is describing is a lot like solving a puzzle. It can be quite rewarding. Heck, just look at all the fun I’m having.

Sources: Ubick, D., P. Paquin, P. E. Cushing, and V. Roth (eds). 2003. Spiders of North America: an identification manual. American Arachnological Society. 377 pp.