Ticks

It is often assumed that entomologists and arachnologists find no kind of arthropod to be revolting; that we never swat a mosquito, and that we vigorously advocate that the public refrain from bringing purposeful harm to any of the six- or eight-legged. Well, we have our limits. While I have a mild fascination with ticks, I don’t tolerate their presence on my body, my pets, or anyone else’s for that matter. There are good reasons to be vigilant when it comes to these parasitic mites, and Lyme Disease is only one. Bites from ticks can result in a variety of illnesses, including “heartland virus,” discovered earlier this year.

Male American Dog Tick

Tick types
North American ticks fall into two basic categories: Hard-bodied ticks, family Ixodidae, and soft-bodied ticks (Argasidae). Soft ticks are encountered infrequently, most species being associated with the burrows and nests of rodents, or with bats. A few are hosted by deer and livestock. Hard ticks are abundant, widespread, and nearly impossible to avoid.

Soft-bodied tick, Arizona

Tick biology
Ticks have a life cycle consisting of four stages: egg, larva, nymph, and adult. Larvae have only six legs, and are often referred to as “seed ticks.” The larva takes one blood meal from a host, then drops off the animal. It molts into an eight-legged nymph in about one week. The nymph locates a host and feeds, drops off, and molts into either another nymphal stage or an adult. Adult ticks are sexually mature specimens, whereas the preceding life stages are not.

"Questing" wood tick, California

Ticks find hosts by a behavior known as “questing.” The tick climbs to the tip of a grassblade, leaf, or other object and perches with front legs outstretched. Special sense organs in the legs detect carbon dioxide breathed out by vertebrate animals. Additional sensory organs hone in on odors and body heat. Ticks usually grab a passing host, but they can quickly crawl 10-15 feet to reach a source of carbon dioxide, such as a grazing deer.

Embedded tick nymph

How ticks attach
Ticks bite with mouthparts that, under high magnification, resemble a Swiss army knife of sawblades. The paired chelicerae (“jaws”) saw into the skin of the host, and later tear into tiny capillaries to get the blood flowing. The central, harpoon-like mouthpart is called the hypostome, and that is the tube the tick uses to inject saliva and anti-coagulants, as well as siphoning the blood of the host. The chelicerae anchor the tick in place, but the tick also secretes a glue-like substance that hardens around the entire apparatus. No wonder ticks are so hard to remove once they lodge themselves into a person or pet.

Engorged female American Dog Tick

Tick feeding and reproduction
The exoskeleton covering the abdomen of a female tick is deceptively thick, leathery, and wrinkled, but capable of unbelievable expansion to accommodate a gut that swells with blood. She may balloon to twenty or fifty times her normal size, and up to 200 times her original weight before feeding. She needs the nourishment to produce her eggs….

And ticks are nothing if not prolific. Mating may take place before or after feeding, and on or off of a host. Females are typically larger than males, and often marked more ornately. The two genders find each other through pheromones, chemical scents emitted into the air. Each mated female lays large masses of eggs, some containing up to 20,000 ova. The eggs may be laid on or off of a host.

Blacklegged Tick, © Karl Hillig via Bugguide.net

Deer Ticks
The tick that most often makes the news is the Blacklegged Tick, Ixodes scapularis (formerly known as I. dammini). This is the “deer tick” that vectors Lyme disease, named for the town of Old Lyme, Connecticut where it was first discovered in 1975. The disease was actually known from Europe as early as 1910, where it went by the name erythema migrans, roughly translated to “migrating red rash.” The organism that causes the disease is a spirochaete bacterium, Borrelia burgdorferi.

I won’t go into the particulars about Lyme disease, as there are plenty of other resources available. Contrary to popular belief, only the adult ticks feed on larger mammals like deer. The larvae and nymphs are hosted by birds and rodents. Increasingly, all host reservoirs are becoming more and more adapted to urban and suburban habitats, increasing human exposure to their pathogens and parasites. The Blacklegged Tick is also a vector of babesiosis; and its bite can cause tick paralysis.

The Western Blacklegged Tick, Ixodes pacificus, is the only other known carrier of Lyme disease. Incidences of the disease in west coast states, Utah, southern Nevada, and northwest Arizona are likely attributable to this tick species.

Heartland virus was discovered earlier this year in northwest Missouri. Initially, two patients were thought to be victims of ehrlichiosis, another tick-borne disease, but the patients failed to respond to treatment. Ticks have not been identified conclusively as the vectors of Heartland virus, merely implicated thus far. Deer ticks are substantially smaller than the next two species discussed here.

Female Lone Star Tick

Male Lone Star Tick

Lone Star Tick
Lyme and Heartland may make headlines, but ticks are responsible for a surprising array of medical problems. I recently visited Missouri with my wife, and we were both plucking ticks off ourselves and each other. The first ones I found were Lone Star Ticks, Amblyomma americanum. Females are easily recognized by the bright yellow or ivory spot on their backs. Males are smaller, with a few pale spots along the margin of the abdomen. This tick is well known as a vector of ehrlichiosis, tularemia, and Southern Tick-associated Rash Illness (STARI). It has also been implicated in the transmission of tick paralysis, and suspected as a vector of Q-fever. White-tailed deer are the principal host of all life stages of the tick, though larvae and nymphs are also found on birds.

Male American Dog Tick

Wood Ticks
The other tick we found was the ubiquitous American Dog Tick, Dermacentor variabilis. We even pulled one off of our dog, who we had left with relatives in Kansas for a short time. Rocky Mountain Spotted Fever and tularemia are carried by this species. Tick paralysis is another malady caused by this species, and it is also a suspected carrier of ehrlichiosis. Larvae and nymphs of the American Dog Tick feed on small rodents, while the adults are hosted mostly by medium-sized mammals.

Ticks and pets
It is important to note that Fido can suffer from Lyme disease, too, and also anaplasmosis, another tick-borne ailment attributed to Blacklegged Ticks. Ask your veterinarian for the best ways to keep your pet from getting ticks.

Inspecting for ticks; and preventing them
Ticks have an uncanny ability to remain undetected until they find a spot to feed. Most people cannot feel a tick crawling on their body. Furthermore, ticks have a nasty habit of attaching in places you can’t readily see yourself: the small of your back, behind your knees, or behind your ears. It is recommended that you ask someone to help inspect you for ticks as soon as possible after an outdoor trek where ticks are likely to be found.

You can try to prevent ticks by wearing a longsleeve shirt, tucked into your pants, and with cuffs that fit tightly around your wrists. Long pants, the cuffs tucked into your boots, will help keep ticks at bay, too. Light-colored clothing is best because ticks are dark and more easily visible on beige or other pale colors. Insect repellants with DEET as the active ingredient have at least some efficacy in protecting you from ticks, but apply them correctly according to label instructions.

Female Lone Star Tick

Sources: Drummond, Roger. 1998. Ticks and what you can do about them (2nd edition). Berkeley: Wilderness Press. 74 pp.
Centers for Disease Control. “Ticks”

Priocnemis minorata

One of the more conspicuous wasps of springtime in deciduous forests of the eastern United States is the spider wasp Priocnemis minorata. Indeed, it is usually the first member of the family Pompilidae to be seen. You can find them right now, as I did in Missouri last week.

These are medium-sized insects, the length of the front wing varying from 6-12 millimeters, the entire insect a bit longer. Their long legs make them appear even larger overall. They are shiny black in color, with the wings having a smoky and/or iridescent appearance. Note the serrated top surface of the tibia (“shin” segment) on the hind leg. This character immediately sets them apart from other black spider wasps you are likely to encounter. Look for them hunting among leaf litter in places where there is dappled sunlight through the tree canopy. The wasps are active from late March to mid-June, with peak activity in April and May.

While this species is most abundant in the U.S. east of the 100th meridian, it has also been recorded from the Pacific Northwest in southeast British Columbia and western Oregon. Additional Canadian records include Nova Scotia, Quebec, and Ontario.

Priocnemis minorata is a generalist predator of spiders, and probably an opportunist. Known host records include Coras juvenilis, Wadotes calcaratus, Wadotes hybridus (hacklemesh weavers, family Amaurobiidae), Hibana gracilis (ghost spiders, family Anyphaenidae), Clubiona obesa (sac spiders, family Clubionidae), Dolomedes tenebrosus (fishing spiders, family Pisauridae), Trochosa terricola, Gladicosa gulosa, Arctosa rubicunda, and Varacosa avara (wolf spiders, family Lycosidae).

Last week I found the female specimen shown here at The Inn on Crescent Lake in Excelsior Springs, Kansas, that oddly persisted in staying in one place. Eventually, I figured out that she was in the process of carting off a paralyzed, immature nursery web spider, Pisaurina mira (family Pisauridae). It turns out this is not a new host record, as this spider species was discovered as a host for Priocnemis minorata previously (Kurczewski, et al., 1987).

Dick Walton has captured some stunning video of this species in action, including what might be a new host record: a running crab spider in the genus Thanatus (family Philodromidae). He also shows another specimen dispatching a wolf spider.

The female wasp digs a burrow prior to going hunting. The entrance is usually hidden under dead, dry leaves. The tunnel itself is vertical or slightly angled, and may reach a depth of 27.5 centimeters. One cell is constructed at the bottom of the shaft, with as many as six other cells branching off progressively from the bottom up. One spider is apparently stored in each cell, on its side, with an egg laid on the spider’s abdomen. The egg hatches in two days and the larva that hatches matures in about a week. The remainder of the year is spent in the pupa stage, until the adult wasp emerges the following spring.

When I lived in Cincinnati, Ohio, I could always tell when spring had really arrived by when the spider wasps were out. I encourage you to look for this species in your own neck of the woods, among the trilliums, violets, and other wildflowers on the forest floor.

Sources: Evans, Howard E. and Carl M. Yoshimoto. 1962. “The Ecology and Nesting Behavior of the Pompilidae (Hymenoptera) of the Northeastern United States,” Misc. Publ. Entomol. Soc. Am. 3(3): 67-119.
Kurczewski, Frank E. and Edmund J. and Roy A. Norton. 1987. “New Prey Records for Species of Nearctic Pompilidae (Hymenoptera),” J. Kans. Entomol. Soc. 60(3): 467-475.
Townes, Henry. 1957. “Nearctic Wasps of the Subfamilies Pepsinae and Ceropalinae,” US Nat. Mus. Bull. No. 209. 286 pp.

Velvet-striped Grasshopper

Another springtime grasshopper one is likely to encounter east of the Rocky Mountains is the Velvet-striped Grasshopper, Eritettix simplex. It is classified as one of the “slant-faced grasshoppers,” though its head is only slightly inclined.

This species passes the winter as a third-, fourth-, or fifth-instar nymph, with adults obvious in early spring most years. This year I have yet to see a mature individual, though I saw nymphs early on. Even the adults are rather small, females measuring 19-26 millimeters, and males 14-21 millimeters from head to the tips of the folded wings.

Individuals vary drastically in color and pattern, such that they can easily be mistaken for other grasshopper species. The one below I mistook for an Obscure Grasshopper, Opeia obscura, but David Ferguson, an expert on Colorado grasshoppers, set me straight. The pattern of stripes on the thorax of this specimen is rather unusual for E. simplex.

Some individuals even have extensive green markings, a good disguise for that time of year when new shoots are sprouting amid dry, brown dead grassblades. These insects are essentially invisible until you flush one into a hop or flight.

The male literally rocks the courtship thing. He will follow the object of his desire until he is about an inch away from her, then begin rocking from side to side. He then “sings” to her by rubbing one hind leg at a time against a raised vein on each front wing. After a chorus of this, like a fool he rushes in, mounting her. Mating takes place if she approves of her suitor.

The Velvet-striped Grasshopper ranges from extreme southern Saskatchewan to Arizona and northern Mexico, east through southern Minnesota, Iowa, Missouri, and northern Arkansas, reaching an eastern bottleneck through Tennessee, and expanding again into northern Georgia, eastern West Virginia, Connecticut, and the southeast corner of New York. It occurs in the Atlantic states, but is absent from the coastal plains. It apparently prefers shorter grasses in the tallgrass prairie biome, but I find it commonly in shortgrass prairie habitats, or mid-height grasses in open areas with patches of barren soil. In desert habitats it prefers moist swales.

nymphs

There are two other species of Eritettix in North America, but both species have abbreviated wings that do not reach the tip of the abdomen in adults. E. abortivus occurs throughout much of Texas and into southeast New Mexico and southern Oklahoma, while E. obscurus is restricted to Florida.

The Velvet-striped Grasshopper and its relatives are considered to be of no economic consequence, their populations seldom rising to even potentially destructive levels. They feed almost exclusively on grasses and sedges.

Sources: Branson, David, et al. 1994. “Brownspotted Grasshopper, Psoloessa delicatula (Scudder),” Wyoming Agricultural Experiment Station Bulletin 912
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.
Eaton, Eric R., Tom Bentley, and David Ferguson. 2010. “Species Eritettix simplex - Velvet-striped Grasshopper,” Bugguide.net

Brown-spotted Range Grasshopper

The Brown-spotted Range Grasshopper, Psoloessa delicatula, is one of the smaller of the springtime grasshoppers here on the Front Range in eastern Colorado. I have only seen one so far this year, but considering it snowed yesterday, May 1 (yes, that is not a typographical error, it really snowed on May Day), I can’t be too surprised by their lack of abundance.

Mature females of this species are only 16-27 millimeters from head to wingtip, males 18-20 millimeters. As if size alone doesn’t make them hard enough to spot, their ornate crisscross markings render them nearly invisible among the tangles of short grasses they like to dwell in. One way I recognize them most easily is by the large brown triangle on the top of each hind femur (“thigh”), that is clearly visible when looking down on the insect. Even nymphs have this marking.

nymph

Psoloessa delicatula is nearly identical in appearance to the Texas Spotted Range Grasshopper, P. texana. There is almost no reliable way to separate the two in the field without capturing a specimen and examining it very closely. Still, David Ferguson, an expert on Colorado grasshoppers, tells me that the Brown-spotted Range Grasshopper is decidedly more robust, or “stockier” as he puts it, than its Texas counterpart. That is perhaps no help if you have not seen both species, and/or you are looking at a female of one and a male of the other. Female grasshoppers are definitely the more robust gender.

The Brown-spotted Range Grasshopper is common from south-central Canada to northern Mexico, and eastern Washington, Oregon, and California to the Dakotas, Nebraska, western Kansas, the panhandle of Oklahoma, and western Texas. The Texas Spotted Range Grasshopper is more southerly in its distribution, from southern California east to central Texas and north to South Dakota.

Adults of the Brown-spotted Range Grasshopper are most abundant in May and June over most of its range. Eggs are laid in barren soil in mid-summer, and the nymphs overwinter. They emerge again in April to finish maturing, having only one or two molts left before reaching adulthood. In central Saskatchewan, this species has a two-year life cycle.

Populations of this species vary with winter survivorship of the nymphs, but seldom if ever become problematic to ranchers and farmers. The insects feed exclusively on grasses and sedges, but do not eat enough to deprive livestock of forage.

You may have to flush one of these grasshoppers numerous times before you can find where it landed after its short flight. They are incredibly cryptic. Good luck!

Sources: Branson, David, et al. 1994. “Brownspotted Grasshopper, Psoloessa delicatula (Scudder),” Wyoming Agricultural Experiment Station Bulletin 912
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.